Although Acremonium strictum is environmentally widespread as opportunistic mold, it may cause infection in patients who have immunodeficiency problems. In this study, Staphylococcus aureus and A. strictum were isolated from the pleural fluid of a patient with colon adenocarcinoma. The patient did not receive antifungal therapy because the patient died after the isolation of mold. The minimal inhibitory concentrations of amphotericin B, fluconazole, ketoconazole, itraconazole, voriconazole for the A. strictum strain isolated from pleural fluid were 0.125, 256, 2 and 1.5, 0.25 μg ml⁻¹ respectively. In conclusion, bacteria and fungus, especially opportunistic mold, should be taken into consideration in developing pleuritis in the patients with immune‐deficiency.