Serious infections (SI) impair quality of life and increase costs. Our aim was to determine if sarcoidosis is associated with a higher rate of SI and whether this varies by age, sex, time since diagnosis, or treatment status around diagnosis.We compared individuals with sarcoidosis (≥2 ICD codes in the Swedish National Patient Register 2003-2013; n=8737) and general population comparators matched 10:1 on age, sex, and residential location (n=86 376). Patients diagnosed 2006-2013 who were dispensed ≥1 immunosuppressant ±3 months from diagnosis (Prescribed Drug Register) were identified. Cases and comparators were followed in the National Patient Register for hospitalisations for infection. Using Cox and flexible parametric models, we estimated adjusted hazard ratios and 95% confidence intervals (aHR;CI) for first and recurrent SIs (new SI >30 days after the previous).We identified 895 first SIs in sarcoidosis and 3881 in comparators. The rate of SI was 1.8-fold increased in sarcoidosis compared to the general population (aHR 1.81 [95%CI 1.65, 1.98]). The aHR was higher in females than males and during the first 2 years of follow-up. Sarcoidosis cases treated with immunosuppressants around diagnosis had a threefold increased risk whereas non-treated patients had a 50% increased risk. The rate of SI recurrence was 2.8-fold higher in cases than in comparators.SIs are more common in sarcoidosis than in the general population, particularly during the first few years after diagnosis. Patients who need immunosuppressant treatment around diagnosis are twice as likely to develop a serious infection than those who do not.