Eulemur flavifrons is a medium-sized lemur with a head-body length of 39–45 cm, a tail length of 51–65 cm, a total length of 90–100 cm, and a weight of 1.8–1.9 kg (Terranova and Coffman, 1997; G. Randriatahina, pers. comm.). This species is sexually dichromatic. In males, the dorsal and ventral coats are black, the hairs sometimes tinged with brown, and a distinct ridge of hair on the forehead forms a noticeable crest. In contrast to E. macaco, with which it was long considered conspecific, there are no ear tufts. In females, the dorsal coat is reddish-tan to reddish-gray. The ventral coat is creamy-white to gray. The hands and feet are darker gray. The muzzle is slate-gray, the face lighter, and the crown rufous-tan. As with males, and again in contrast to female E. macaco, there are no ear tufts. The eyes of both sexes are blue to blue-gray, making this species one of the very few primates in the world that consistently has blue eyes, hence the common English name. The taxonomic status of this lemur has been debated since it was first described in the late 1800s. Due to the lack of locality data for the few museum specimens collected, nothing was known of its status in the wild until its “rediscovery” in 1983 (Tattersall, 1982; Koenders et al., 1985a). Subsequent genetic analysis indicated that it was distinct. It was at first separated as a subspecies (Fausser et al., 2000), but we elevate it here to a full species (Mittermeier et al., 2008c). The blue-eyed black lemur can only be confused with the black lemur, which is found just to its north and with which it is reported to hybridize in a large area of the Manongarivo Special Reserve. The lack of ear tufts in E. flavifrons and its striking blue-gray eyes readily distinguish it from Eulemur macaco.