Abstract: Objective To make an epidemiological investigation on malaria in Motuo County，Linzhi Prefecture of Tibet. Methods In July of the year 2006，the following activities were conducted in 2 selected villages from each of the three townships，i.e.，Motuo，Dexing and Beibeng：malaria history survey among inhabitants in recent 2 years; collection of blood samples of inhabitants for examining malaria parasites，IFAT and detecting G6PD，respectively; mosquito collection in human dwellings and cattle shelters at night and various resting sites at day-time; mosquito collection by outdoor human baiting capture; classification and composition calculation of mosquito species and manbiting rates; ELISA for detecting sporozoite infection of Ａnopheles. Results The mean rate of two-year malaria history was 8.98%（118/1 314） and the parasite rate was 3.13%（38/1 216， all P. vivax） in the inhabitants. The parasite positive rate among the feverish patients was 7.14%（3/42）. IFAT revealed a malaria antibody rate of 40.24%（472/1 173）. The G6PD deficiency rate was 1.74%（21/1 208）. Five hundred and thirteen anopheline mosquitoes were caught. They were An. maculatus（474） which occupied 92.4%（474/513）， An. peditaeniatus（35），An. kochi（3）and An. sinensis（1）. The mean indoor density of An. maculatus was 4.75/night in human houses，and 69.5/night in cattle shelters. The outdoor human biting rate was 22.75/half-night/person，and the sporozoite rate of An. maculatus in anopheline saliva glands was 0 by ELISA. Conclusion Motuo County is an endemic area of vivax malaria with An. maculatus as the potential vector.

Key words: Motuo County, Malaria, Epidemiology, Survey, Tibet