Toxoplasma gondii is an opportunistic parasite that can cause severe disease in immunosuppressed individuals. We report a case of unsuspected T. gondii empyema in a bone marrow transplant recipient that was diagnosed by the visualization of numerous intracellular and extracellular tachyzoites in Giemsa- and Gram-stained smears. The patient was treated with pyrimethamine, sulfadiazine, clindamycin, and atovaquone, and she survived 110 days after diagnosis, despite having a large parasite burden.