Objective To summarize the clinical features of patients with polymyositis and malignancy . Methods We retrospectively reviewed the clinical records of patients with polymyositis and malignancy hospital -ized at Peking Union Medical College Hospital from October 1989 to June 2013.Results Malignancy was identi-fied in 2.4% (10/424) of patients with polymyositis in the hospital during the studied period .The median age of the 10 patients (3 males and 7 females) was 57 years.All patients had significant proximal muscle weakness .Dif-ficulty in head-lifting, bucking, and hoarseness were each observed in one case .Interstitial lung disease , respirato-ry muscle involvement , and cardiac involvement were observed in 5, 2, and 6 patients, respectively .The most common types of cancer were lymphoma and lung cancer (3 cases each).Other types included esophageal , gastric, renal, and cervical cancers (1 case each).Malignancies in 7 cases were discovered within 1 year before or after polymyositis diagnosis .The initial demonstrations of malignancies included lymphadenectasis , cough and dyspnea , dysphagia, gross hematuria , and postmenopausal vaginal bleeding .Three asymptomatic patients were identified through screening based on positive feces occult blood test or lung mass .Five out of the 9 patients receiving ade-quate dose of glucocorticoid recovered completely from polymyositis within 1 month, whereas the remaining 4 pa-tients improved but did not fully recover .Of the 4 patients, 3 patients achieved complete recovery after treatment for cancer.Conclusions Malignancy may interfere with the treatment response and prognosis of polymyositis , there-fore patients with polymyositis should have a complete screening for the underlying malignancy .Early cancer treat-ment should be prescribed to better mitigate symptoms and manage conditions in patients with polymyositis and cancer .