Autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy (APECED) is an autoimmune endocrinopathy with severe and unpredictable course. The impact of APECED on mortality has not been determined.To assess overall and cause-specific mortality of patients with APECED.and Setting: A follow-up study of Finnish patients with APECED in 1971-2018. Causes and dates of death were collected from Finnish registries.Ninety-one patients with APECED.Overall and cause-specific standardized mortality ratios (SMRs) determined by comparing the observed numbers of death and those expected on the basis of respective population death rates in Finland.The overall disease mortality was significantly increased [29 deaths, SMR 11; 95% confidence interval (CI) 7.2-16; p<0.001]. The relative risk (SMR) was highest in the youngest age groups but the absolute excess risk was similar (about 10 per 10,000 person-years) in all age categories. The highest SMRs were seen for endocrine and metabolic diseases (SMR 570; 95% CI 270-1000; p<0.001) and for oral and esophageal malignancies (SMR 170; 95% CI 68-360; p<0.001). Mortality was also increased for infections, diseases of digestive system, alcohol-related deaths, and for accidents. Due to small number of cases we were unable to evaluate whether mortality was affected by disease severity.Patients with APECED have significantly increased mortality in all age groups. Highest SMRs are found for causes that are directly related to APECED but also for infections. Increased alcohol- and accident-related deaths may be influenced by psychosocial factors.