ObjectiveTo study the survival rate and death cause of patients with polymyositis (PM) and dermatomyositis (DM). MethodsBased on the Bohan and Peter diagnosis standard, DM (n=52) and PM (n=98) hospitalized patients between January 1, 2008 and January 1, 2013 were chosen to be followed up to January 2013, or to their death. Sex, age, disease entities, course of the disease, muscle creatine enzyme, interstitial lung disease, connective tissue diseases, lung infection, cardiac involvement, respiratory muscle paralysis, JO-1 antibody, hypoalbuminemia, tumor, and long-term hormone and immune inhibitor treatment were the influencing factors of death. ResultsThirty-eight patients died during the follow-up period, and the 1-, 3- and 5-year survival rate were 87.7%, 74.5% and 55.9% respectively. Cox regression analysis showed that interstitial pneumonia (RR=12.119, P=0.001), heart disease (RR=2.935, P=0.020) and tumor (RR=3.735, P=0.048) were the unfavorable factors of death, while long-term hormones (RR=0.329, P=0.024) and persistent immunosuppressant therapy (RR=0.148, P=0.022) were protective factors. ConclusionThe five-year survival rate of patients with PM/DM is still low, and pulmonary interstitial disease, tumor, cardiac involvement, and pulmonary infection are the major dead causes, while long-team immunosuppression and hormone therapy can decrease the PM/DM mortality.