Echinococcus multilocularis, the causative agent of alveolar echinococcosis, is spreading geographically in Europe, and prevalence rates in foxes, the final host, are increasing. Concomitantly, the rate of newly diagnosed human infections has already doubled in Germany. We report a cluster of alveolar echinococcosis in 24 animals of different Old World monkey species (15 cynomolgus monkeys, 5 rhesus monkeys, and 4 lion-tailed macaques) in northern Germany. The cluster described is the largest ever recorded in a single center. Cynomolgus monkeys were very susceptible and constituted the monkey species at highest risk, indicating that this species could act as a sentinel animal for the transmission of alveolar echinococcosis in zoological gardens or similar institutions.