Abstract: Exoerythrocytic stage: On the 7th day after sporozoite inoculation, intact crypto-zoites generally appear irregularly in outline; some of them may be lobed and some may contain 1-4 vacuoles 4-6μm in diameter; their peripheral nuclei arrange at random, maturing at the 8th day. Parasitemia may appear by the end of the 8th day. The relapse rate of this parasite in Macaca mulatta is about 62.5%.Blood stage: The parasites prefer to invade the 4th stage reticulocytes. Trophozoite--induced infections could be maintained for over 7 years.Sporogony: It takes place in Anopheles dims, A. stephensi and A. lesteri, the first two species being more susceptible than the last one. Oocysts are round or elliptical in shape, they measure 35±5.2μm in diameter at the 8th day and 60μm at the maxi-mum; sporozoites can be found in the salivary glands at the 8th day.Based on the findings mentioned above, this malaria parasite may be considered as the Cambodian strain of Plasmodium cynomolgi.