Different species of Saimiri and Aotus monkeys were inoculated with sporozoites of the Salvador I strain of Plasmodium vivax. Of 58 Saimiri inoculated, 45 developed parasitemia (4 following bites and 41 following intravenous inoculation). Prepatent periods ranged from 10 to 63 days. Twelve of 19 monkeys inoculated with sporozoites that had been stored frozen developed patent parasitemia after 16-53 days. Of 41 Aotus monkeys inoculated, only 10 (2 via bites and 8 via intravenous inoculation) developed parasitemia. One of 7 Aotus inoculated with sporozoites that had been frozen developed parasitemia with a prepatent period of 26 days. Mosquitoes were infected by feeding on gametocytes from Aotus and Saimiri monkeys, chimpanzees, and a human. Sporozoites from Anopheles stephensi, Anopheles freeborni, Anopheles dirus, and Anopheles gambiae induced infection.