The aims of this national cohort study were: (1) to evaluate mortality in patients with sarcoidosis, stratified by gender, age and systemic corticosteroid (SC) treatment and (2) to characterize comorbidities in this cohort. Patients diagnosed with sarcoidosis from 2001 to 2015 were identified in the Danish National Patient Registry. Subgroup analyses were performed on cases treated/not treated with SCs within 3 years of the initial sarcoidosis diagnosis (as a proxy for disease severity). The Deyo-Charlson Comorbidity Index was used to evaluate pre-diagnostic comorbidity. Cases were matched (1:4) with controls from the general population. We identified 9795 cases with sarcoidosis. Mean age was 46.5 ± 15.9 years and 55% were male. The adjusted hazard ratio (HR) for death was 1.48 (95% CI 1.31-1.68). Mortality was higher than for controls in all age groups and in both genders. HR for death for cases treated with SCs was 1.78 (95% CI 1.49-2.13) and, for cases receiving no treatment, 1.24 (95% CI 1.04-1.48). Sarcoidosis was the most commonly registered cause of death (13.3%). Patients with sarcoidosis have an increased mortality compared with matched controls. Mortality is particularly high in patients treated with SCs.