Objective To investigate the changes of major causes of death in patient with dermatomyositis/polymyositis (DM/PM) and the factors affecting the mortality of DM/PM in the past 28 years.Methods Death cases with DM/PM from 1985 to 2013 were retrospectively analyzed.x2 test and Fisher exact test was used for count data analysis;independent samples t-test measurement was used for data analysis;P＜0.05 was consi-dered statistically significant.Results Out of 1 443 patients with DM/PM, 74 died, in whom 48 were female and 26 were male.The mortality rate was 4.7％ among female and 6.3％ among male cases and the total in-hospital mortality of DM/PM was 5.1％.The two most common causes of death in patients with DM/PM were infection and respiratory involvement, accounting for 62.2％ (46/74) and 14.9％ (11/74) respectively.Death occurred most commonly in the first year after disease onset, accounting for 79.7％(59/74).The leading causes of death in the first year were infection and respiratory involvement.The mortality of DM/PM patients was peaked 12.3％(18/146) from 1996 to 2000;infection was the most frequent cause of death.Conclusion Infection and respiratory involvement are the main causes of death in DM/PM.Death occurrs most commonly in the first year after disease onset.