Pembrolizumab, an anti-programmed death-1 monoclonal antibody, has been approved by the Food and Drug Administration in 2014 on the basis of improved progression-free and overall survival in metastatic melanoma. We report for the first time a successful treatment with a programmed death-1 antibody in a 69-year-old metastastic melanoma patient with a Churg-Strauss lung vasculitis and a prior ipilimumab-induced autoimmune colitis. This case report suggests that pembrolizumab can be given with caution to patients with underlying autoimmune disease. As the use of checkpoint inhibitors expands, knowledge about their safety in patients with underlying autoimmune diseases will become increasingly important, in particular because these patients are typically excluded from clinical trials with immune-checkpoint inhibitors.