Despite proven efficacy of alemtuzumab in multiple sclerosis (MS), approximately 50% of individuals will develop a new autoimmune disease following treatment. To date these have largely been antibody mediated and organ specific (primarily affecting the thyroid gland). In a retrospective case series of 187 patients from two UK specialist centres (Cardiff and Cambridge) followed up for a median of 10 years, we report 3 (1.6%) cases of sarcoidosis following alemtuzumab treatment of MS. This report increases the spectrum of auto-inflammatory disease following alemtuzumab and should be considered by clinicians when using this therapeutic agent for MS.