In order to better understand experimental strongyloidiasis in small New World primates, and to evaluate aspects of reinfection and immunosuppression induced by glucocorticoids, nine specimens of Callithrix penicillata (Primates: Cebidae) were administered (by subcutaneous injection, sc) 3000 infective larvae of a strain of Strongyloides venezuelensis (Rhabditida: Strongyloididae) that had been maintained in successive passages through AKR/J mice since 1987. The mean prepatent period was 5.6 ± 0.7 days post-infection (DPI). The mean patent period of infection among the untreated animals (marmosets 1-7) was 123.4 ± 61.4 DPI. Two animals (marmosets 8 and 9) received dexamethasone (2.5 mg/kg, sc) for five consecutive days starting on the 20th day after infection, but this treatment did not alter the course of the infection, and the patent period for these animals was 100.5 ± 58.7 DPI (59 and 142, respectively). Stool examination showed that the highest quantities of parasite eggs were expelled between the 8th and 19th days after inoculation of the larvae. Thereafter, there was a gradual reduction in the number of parasite eggs in feces of all marmosets. During the chronic phase of the infection, before completely negative parasitological findings were obtained, the parasitological examinations were intermittently positive. Reinfection of three of these animals did not result in new positive examinations. However, given the receptiveness of these animals to initial infection with S. venezuelensis and their similarities to human beings, it is proposed that C. penicillata could be used as a nonhuman primate model for experimental strongyloidiasis.