Two subspecies are recognized: Zamenis l. longissimus (Laurenti, 1768) is widely distributed in western, central and southern Europe, except in southern Italy and Sicily where it is replaced by Z. lineatus; and Z. l. rechingeri Werner, 1932 is found in the larger Cyclades islands, in particular on Amorgos.

European regional assessment: Least Concern (LC)
EU 27 regional assessment: Least Concern (LC)

The species is widespread in Europe and is assessed as Least Concern for both Europe and the EU27 Member States in view of its wide distribution, presumed large population, and although it is believed to be declining in much of its European range it is unlikely to be declining fast enough (at a rate of 30% or greater) to qualify for listing in a threatened category for Europe or for the EU27 Member States.

Within the European region, this species ranges from northern Spain (from Santander to Barcelona), through much of France (south of Paris) and central-southern Italy (south to northern Campania and the border between Basilicata and Apulia - Salvi et al. 2017), and through "large parts of C and E Europe" from Switzerland to Greece, although it is absent from most Greek islands other than Corfu, Paxos and Samothrace (Speybroeck et al. 2016). The species occurs in a number of isolated subpopulations across and beyond its core range - including the Cantabrian Mountains in Spain, southern Ukraine (Speybroeck et al. 2016), and "c.10" isolated subpopulations across western Germany, the northern Czech Republic and Poland - possibly relicts of a wider Holocene distribution (Allentoft et al. 2018). Five northern subpopulations have become extinct within the last 150 years including the only known Danish subpopulation, which apparently represented the species' historical northern range limit (Allentoft et al. 2018), although there are recent records of the species from Denmark that require confirmation. There are few records from Romanian Moldova but it is thought likely to be widespread in this region, although likely at low densities (Strugariu et al. 2016). Records from Sardinia are considered doubtful (Speybroeck et al. 2016).

In southern Italy the relative range limits of Zamenis longissimus and Z. lineatus are not clear, a situation complicated by the discovery of intermediate forms and the lack of standard procedures for distinguishing the two species (Salvi et al. 2017). These authors investigated the distributions of the two taxa in Italy and found that in the Apulia region at least some morphologically intermediate specimens were referrable to Z. longissimus, with none that could be unambiguously assigned to Z. lineatus. Pending more detailed research, Apulia can tentatively be included within the range of Z. longissimus (D. Salvi pers. comm. 2022).

Introduced subpopulations have been established in the UK since the 1960s, where viable subpopulations are known from the Welsh Mountain Zoo in northern Wales and Regent's Canal in London, and it was recorded from Bridgend in South Wales for the first time by Clemens and Allain (2020). The species likely established itself following escapes from zoos, which are close to both previously known localities. The Brigend subpopulation - thought to have been established since the early 2000s - is likely to have be the result of the pet trade (Clemens and Allain 2020). The species was also introduced north of its natural Swiss range at a site near Lac de Bienne in 1994 (Hofer 2001). Isolates elsewhere in northern and central Europe have been proposed as having a non-native origin, discussed by Musilová et al. (2007); these authors concluded that the available evidence suggests a native origin for these.

The global range extends out of Europe to northern Türkiye, western Georgia, southern Russia (Edgar and Bird 2006), southern Azerbaijan and north-western Iran. It ranges from 60 to 2,000 m asl (Arnold 2003).

This species can be common, and even abundant in some forest types (Geniez 2018), but many subpopulations are small and isolated. In Denmark, the species was last recorded in 1863 (Musilová et al. 2007), however, there are more recent unconfirmed records from the country, and the Denmark national Red List assessment has been revised from RE to DD. Edgar and Bird (2006) report that it is "rarely considered" to be abundant and is apparently in decline. It is thought either to be elusive or to occur in low densities in Romania east of the Siret River (Strugariu et al. 2016). Systematic studies since the 1980s in Germany indicate that it is undergoing a "moderate decline" in habitat quality due to land use change, and a similar decline in the population is assumed in the national Red List (Rote-Liste-Gremium Amphibien und Reptilien 2020). A study modelling population trends based on citizen science data collected between 1980 and 2017 (Spain) and 1980 and 2018 (Languedoc, France) found that the population was stable in Spain over this period but had undergone a decline of 87.53% in southern France over this period, corresponding to a decline of 33.66% over a presumed three generation period of 15 years (Santos et al. 2022). In Switzerland, a reduction of 51.4% was noticed in the previous Red List (Monney and Meyer, 2005), whereas, most recently, this reduction was limited to -20% over three generations (OFEV and info fauna, 2023).

This is "the most woodland-dwelling of European snakes" and can be abundant in some low- and mid-elevation woodland habitats, such as open chestnut woodland (Geniez 2018). It is relatively adaptable so long as the climate (relatively mesic, and without "excessive variation" in temperature) is suitable and can be found along riverbanks, in marshland, in clearings, in areas of dense scrub and along hedgerows in farming areas, as well as around abandoned buildings, dry stone walls or disused quarries (Geniez 2018). It can be found around humans in rural areas and may enter houses or sheds (Edgar and Bird 2006). Mating takes place in May with clutches of 2-18 eggs (mean 6.6 based on sources compiled by Santos et al. 2022) hatching in September (Geniez 2018). It can be inactive for 4-6 months in parts of its range (Geniez 2018). It has an assumed generation length of 5 years (Santos et al. 2022), inferred by these authors to be a year later than age at maturity.

This species may be most significantly threatened by deforestation for intensive agriculture, conifer plantations or urban development; agricultural intensification within existing agricultural landscapes that removes traditional hedgerows or dry stone walls also reduces the extent and quality of this snake's habitat (Edgar and Bird 2006). Additional impacts may exist from general habitat degradation due to pesticide use and infrastructure development (Edgar and Bird 2006). Both males and females travel long distances to mate, and road mortality is likely to represent an increasing threat to this species due both to this and its occurrence at low densities (Edgar and Bird 2006). As with many snakes, this species is generally persecuted by people. Eggs are laid in heaps of grass and other vegetation that are frequently cleared by people.

This species is a "fairly popular" pet in the UK (Clemens and Allain 2020). Wild collection has been recorded from several range states - see Edgar and Bird (2006), and most recently from Russia and Moldova), but it is unlikely it is collected in significant numbers (Edgar and Bird 2006).

It is listed on Annex II of the Bern Convention and is included in Annex IV of the EU Habitat Directive. The species is present in a number of protected areas throughout its range.

Conservation actions, such as ecological research and protection of important areas, and needed for subpopulations in Germany, and presumably other northern parts of the species range (CoE 2003). It is protected by national legislation in most range states. There is a need to develop management strategies and protected areas for this species at a national level. An EU Action Plan (Edgar and Bird 2006) is in place for this species. The species was included into the Red Data Book of the USSR (1984), and the Red Data Books of the Russian Federation (2001) - category 2, Georgia (1982) - category 2, and the Ukraine - category 3. This species is listed an Endangered in the German National Red List. This species is listed as Critically Endangered in Poland (B. Borczyk pers. comm.). This species is categorized as Endangered in Switzerland in the last two red lists (Monney and Meyer 2005; OFEV and info fauna, 2023), as Least Concern for Italy (Rondinini et al. 2013), and as DD for Denmark.