Penicililum marneffei is an opportunistic pathogen in patients with immunodeficiency syndrome or in immunocompetent persons living in endemic areas, including Southeast Asia. Successful treatment of the disease requires early diagnosis and proper antifungal therapy. Delayed diagnosis usually leads to death. We present the case of a patient with acquired immunodeficiency syndrome (AIDS), who had had a sexual experience in Southeast Asia, and who presented with fever and a lung cavitary lesion that was found on the chest film. Penicillium marneffei was isolated from fungal cultures of the blood and a lung aspirate. The patient recovered smoothly after antifungal therapy. We also review the associated literature.