The purpose of this report is to describle the first documented case of pneumocystosis in Gabon. Diagnosis was confirmed based on microbiological methods in a 59-year-old immunodepressed HIV-positive man. Diagnosis was further documented by observation of Pneumocystis jiroveci cysts in the broncho-alveolar lavage (BAL) after Gomori-Grocott color reaction. The patient responded well to treatment with Cotrimoxazole, corticoids and oxygen.