A study has been made of the infectivity and the sporogenic development of Plasmodium vivax in Anopheles sacharovi and An. superpictus under experimental conditions. An. superpictus showed a slightly lower rate of feeding on human bait, oocyst development, and sporozoite infection of the salivary glands, with ratios of 89.3 : 100, 89 : 100, and 98 : 100, respectively. An. superpictus completed sporogony in 10–14 days with an average of 11.7 days, and An. sacharovi within 8–12 days with an average of 9.8 days. The survival of infected An. superpictus averaged 16.5 days postinfection while An. sacharovi averaged 11.6 days. Under laboratory conditions, An. sacharovi was a more competent vector of P. vivax than An. superpictus.