Systemic lupus erythematosus (SLE) is an autoimmune connective tissue disease characterised by inflammation. Malignant pleural mesothelioma (MPM) is a highly invasive malignant tumor derived from pleural mesothelial cells. Here, we report a case of SLE with MPM. A 42-year woman with no exposure to asbestos presented with severe left chest pain. Initially, we diagnosed her with SLE because of the clinical manifestations and high antinuclear antibody titer. Finally, a diagnosis of MPM was made, based on pleural biopsy. Her condition was under control after one cycle of chemotherapy and oral methotrexate. However, three years later, she was admitted with dyspnea, mild orthopnea, and tachycardia, and died one month later after discontinuing treatment. MPM is rare, and MPM with SLE is even rarer. We should pay attention to pleural effusion when diagnosing SLE. If possible, a pleural biopsy should be performed to reduce misdiagnosis and missed diagnosis. Key Words: Pleural effusion, Systemic lupus erythematosus (SLE), Mesothelioma.