The population dynamics of a small group of wild chimpanzees at Bossou, Guinea, were studied during a 6.5-year period between 1976 and 1983. The natality rate (0.23 births/female/year) was higher and the interbirth interval (4.3–4.4 years/female) was shorter than those of chimpanzees at East African study sites (the Gombe and Mahale National Parks). The infant mortality for the first 3 years (0.06–0.18/year) was lower than those in East Africa. However, the population had remained almost stable since 1967 (growth rate: 0.985/year). The increase in number by births was offset by the disappearance (perhaps emigration) of adolescent chimpanzees. Adult males immigrated and disappeared (perhaps emigrated) but adult females rarely did.