A case of toxoplasmosis in an adult male emperor tamarin (Saguinus imperator) is reported. The primate was found dead and no clinical sign was noticed before death. Pathological findings included moderate to severe interstitial pneumonia, multifocal necrotizing hepatitis and multifocal to coalescing necrotizing lymphadenitis. Immunohistochemistry assays (strepto-avidin-biotin-peroxidase) performed on paraffin embedded tissues (lung, lymph nodes, liver, spleen, heart, intestine and adipose tissue) were strongly positive for Toxoplasma gondii