Helminths were recovered from 235 (57%) of 412 Panamanian primates. Five species of trematodes, three species of cestodes, 14 species of nematodes, and three species of acanthocephalans were found. Seventeen new host records and 15 new locality records are reported. Spirura tamarini Cosgrove, Nelson & Jones, 1963, is regarded as a synonym of S. guianensis (Ortlepp, 1924). Zonorchis goliath Travassos, 1945, and Echinostoma aphylactum Dietz, 1909, are reported from primates for the first time and Parabronema bonnei (van Thiel, 1925) Diaz-Ungria, 1965, and Controrchis biliophilus Price, 1928, are reported from primates for the third time. Although helminths have been reported from Panamanian primates (McCoy, 1936; Faust, 1935; Caballero et al., 1952), apparently no general survey for these parasites has been made previously in Panama. The present study, while not exhaustive, is a record of helminths found in primates maintained in the laboratory varying lengths of time for malarial studies. From August 1965 to May 1967 helminths were recovered from 235 (57%) of 412 primates autopsied. Table I shows the species distribution of the primates examined, the numbers examined, and the numbers positive. MATERIALS AND METHODS Primates were purchased at the laboratory from native collectors. When an animal died, it was autopsied to determine the cause of death. First, the skin was removed and filarial worms were searched for in the subcutaneous tissues. Next, the internal organs were removed, placed individually in dishes of physiological saline, and either incised or teased apart. The intestinal tract, on being opened, was cut into sections and washed in saline. Any helminths seen were preserved for subsequent study. Trematodes and cestodes were killed with gentle heat, fixed in alcoholformalin-acetic acid solution, stained with Mayer's carmalum, and cleared in methyl salicylate. Acanthocephalans were killed in freshwater in order to make the proboscis protrude, preserved in 70% alcohol, and stained in the same manner as the trematodes and cestodes. Nematodes were killed and preserved in 70% alcohol. They were then studied in lacto-phenol solution and mounted in polyvinyl alcohol containing lacto-phenol. Face-on views of the nematodes were obtained by mounting the heads in glycerine jelly.