Since the introduction of a two-dose MMR vaccination regime the incidence of mumps virus infections has substantially declined. However, mumps outbreaks have recently been reported from several countries. Here we report an ongoing mumps outbreak in Germany. Between 1 July and 31 October, 115 infections have been laboratory-confirmed. Reported complications include one case of meningitis and 21 cases of orchitis, suggesting a high rate of complications. We suggest a vaccination campaign for young adults in northern Bavaria to limit severe mumps infections.