The lesions associated with parasitic infestation in 1156 wild-caught, laboratory-maintained nonhuman primates (Macaca fascicularis, Macaca mulatta, and Papio spp) are described. The two most common parasites seen were lung mites (Pneumonyssus spp) and nodular worms (Oesophagostomum spp). In addition, in cynomolgus monkeys (Macaca fascicularis) only, Nochtia nochti was a frequent pathogen. The etiology of mineralized fibrotic nodules in the mesentery of cynomolgus monkeys was thought to be infection with Paragonimus westermani, the oriental lung fluke.