The forest dormouse, Dryomys nitedula, reaches its southern limit in Israel. This marginal population is confined to Upper Galilee, inhabiting the evergreen maquis of Quercus calliprinos-Pistacia palestina. The animal is active throughout the year in Israel and is mainly nocturnal. Winter activity is interrupted occasionally by short periods of partial or light hibernation. Dryomys is an omnivore and is arboreal, building its nest in trees. Nests are dispersed in groups. Each nest is inhabited by a solitary individual, a pair, or a female and her young. Reproduction occurs between March and December. Two to 3 litters per female occur annually: in spring, summer and autumn. Three is the most frequent litter size. Dryomys is a true hibernator. Starvation and temperatures below 0° C induce deep hibernation in captivity. However, when kept outdoors under conditions similar to its natural habitat, and provided with ample food, only few, short, partial or light hibernation periods ensue, involving a part of the population, during December, January and February.Comparison between Israeli and Eurasian populations of Dryomys discloses variation at least in two physiological features: (a) A full year activity in Israel versus a half year activity. (b) Two-three parturitions per year from March to December in Israel versus one (possibly 2) from May to August. Preliminary observations suggest that these variations might be genetically determined.Maps, graphs, tables and photos show the distribution, habitat, annual activities, nesting habits, reproductive cycle, hibernation and biometric data.