Anopheles darlingi fed on eight falciparum malaria patients with gametocytes before and after treatment with quinine sulfate or quinine sulfate plus tetracycline became infected. Quinine and quinine plus tetracycline had no apparent sporontocidal or gametocytocidal effect on late stage immature and mature gametocytes. Plasmodium falciparum gametocytes are persistent and infected mosquitoes for up to 21 days after patients were treated with quinine plus tetracycline. Sporogonic development was similar for groups of mosquitoes fed before and after patients were treated with these schizontocides. The percentages of infected mosquitoes that developed salivary gland infections were also similar for groups of mosquitoes fed before and after treatment. Twenty-four hours after treatment with 45 mg of primaquine phosphate, falciparum malaria patients were not infective to An. darlingi.