Abstract： Objective To improve the understanding of multiple myeloma (MM).Methods A case of MM with pleural effusion as initial symptom was reported,and relevant literatures were reviewed.Results The female patient was 45 years old,had dyspnoea for three months,and had oliguria,headache and dizziness for nearly one month.Chest computed tomography showed that there were hydropneumothorax in the right,a large number of pleural effusion in the left,and flat hillock-like protuberant soft tissue in the chest wall.Chest thoracoscopic showed that there was massive yellow pleural effusion,the visceral pleura and diaphragmatic pleura were smooth,many nodules on the parietal pleura were variable in size and shape,stiff and hardly hemorrhagic by biopsy.Pathology showed plasmacytoma.By sternal puncture,bone marrow examination revealed a large number of plasmacytoma cells infiltrated bone marrow.Conclusions MM patients with extramedullary disease should be considered to have MM,bone marrow examination should be taken in time to confirm diagnosis.The patient with concurrent extramedullary lesions has poor prognosis.