We report two cases of sporadic Legionnaires' disease in patients with systemic lupus erythematosus who had been receiving immunosuppressive agents. Their chest radiologic findings were characterized by rapidly progressive, multiple cavitary mass-like shadows in bilateral lung field with pleural effusion. Diagnosis was confirmed in both cases by culture from percutaneous needle aspiration of nodule and indirect immuno-fluorescence antibody test for Legionella Pnemophilla rising more than 4 fold in 2 weeks. They showed both clinical and radiographical improvement after treatment of roxythromycin and rifampin or doxycyclin. During the course of therapy, we could maintain the immunosuppressive therapy in both patients.