Large numbers of Plasmodium chabaudi gametocytes can be produced in the splene-ctomized Wistar rats 3-4 days after the intravenous inoculation of high parasitaemia mouse blood. On the 8-9th day, the number of gametocytes reduced greatly. The level of gametocytaemia was related to the time of splenectomy and the amount of the infected blood inoculated. The gametocytes in the rat were normal in their ability of exflagellation and their infectivity to anophelines.