The frequency of fulminant peumonia due to Mycoplasma pneumoniae is relatively rare despite the high prevalence of Mycoplasma species infection in the general population We report a case of mycoplasma pneumonia complicated with severe ARDS, overt hemolytic anemia and hepatitis. He had high titers of antimycoplasma antibody and cold agglutinin. Despite erythromycin administration, the pneumonic infiltration on chest radiography was not resolved, and mechanical ventilation was needed for 16 days. During the therapeutic course, his hemoglobin decreased. After the administration of prednisolone, his hemoglobin increased and pneumonic infitration was totally resolved. He had a progressively favorable course and could be discharged in relatively good clinical condition.