During the recent epidemic of acute anterior poliomyelitis in Panamá the author became interested in experimental studies of the etiologic agent. Three strains of poliomyelitis virus were isolated in rhesus monkeys (Rodaniche, in press). However, in view of the costliness of Macaca mulatta and the delay and difficulty experienced at times in obtaining specimens, it seemed advisable to attempt transmission of the virus to local monkeys. Since Melnick and Paul (1943) and Melnick (1946) had reported successful transmission to South American species of Cebus capucina, the corresponding Panamanian species was chosen for study. Later, experiments were also conducted with two of the four local subspecies of the howler monkey and with juvenile specimens of the black spider monkey. Mackay and Schroeder (1935) were unsuccessful in their attempts to transmit the virus to the South American spider monkey, Ateles ater, but we hoped that perhaps infant and juvenile specimens might prove more susceptible.