Penicillium marneffei, an endemic fungus in Southeast Asia and southern China, is the cause of opportunistic infection in HIV-infected patients who may present with symptoms and signs of the lungs, and abnormal chest radiographs. However, only a few cases of pulmonary infection from this organism have been reported. To study the clinical manifestations of patients with Penicillium marneffei pneumonia diagnosed by sputum or bronchoalveolar lavage (BAL) fluid culture Retrospective descriptive study of patients who were diagnosed with Penicillium marneffei pneumonia at Maharaj Nakorn Chiang Mai Hospital from September 1999 to July 2004. Twelve patients (eight males, four females) were included with mean age of 36.1 years. Nine cases were HIV-infected. Their presenting symptoms included fever, cough, dyspnea and weight loss. Skin lesions, hepatomegaly and lymphadenopathy were extrapulmonary signs. Chest radiographs revealed diffuse reticulonodular, diffuse reticular, localized alveolar, localized reticular infiltration, and cavitary lesion. The diagnosis was made by cultures from the sputum in five cases and BAL fluid in the others. Co-infections with Streptococcus pneumoniae, Klebsiella pneumoniae, Mycobacterium tuberculosis, Cryptococcus neoformans, and Strongyloides stercoralis were found. Most of them were treated by intravenous amphotericin B followed by oral itraconazole, or oral itraconazole. Penicillium marneffei pneumonia has non-specific clinical manifestations, it cannot be excluded from other infections and may have co-infections. Physicians should include this infection in their differential diagnosis especially in immunocompromised patients.