The authors present the first report of Leishmania (Viannia) guyanensis (L.(V.) guyanenesis) associated with human immunodeficiency virus (HIV) in a Brazilian heterosexual man. It is also the first case of HIV infection associated with American cutaneous leishmaniasis in Brazilian Western Amazonia. The patient had cutaneous and mucous lesions with a negative Montenegro skin test. Histopathology showed large numbers of amastigotes, even in a lesion which had clinically healed. L.(V.) guyanenesis was typed by an immunoenzymatic technique. Various therapies were attempted, but the patient relapsed after each episode of treatment.