Over 23 months, zinc toxicosis was diagnosed in 35 baboons aged 5-12 months in one galvanized metal and concrete cage complex with conditions that led to excessive exposure to environmental zinc. Clinical signs included reduced pigmentation of hair, skin, and mucous membranes (whiteness), alopecia, dehydration, emaciation, cachexia, dermatitis, diarrhea and, in six cases, severe gangrenous dermatitis of extremities. The syndrome was characterized by pancytopenia, elevated zinc and low copper serum concentrations, low vitamin D and bone-specific alkaline phosphatase levels, and atypical myelomonocytic proliferation of bone marrow. This syndrome emphasizes the importance of proper husbandry and cage design and indicates the potential of infant baboons as a model to study the effects of excessive zinc on development. This is the first report describing the epidemiologic and clinical presentation of zinc toxicosis in infant baboons in captivity.