Abstract: Stool specimens of 16 079 persons from 32 spots were examined by iodine staining method during 1988-1990. Among the people examined, 2 963 were positive, the overall infection rate being 18.4%. Nine species of protozoa were detected during the survey,namely: Entamoeba histolytica (0.5%), Entamoeba coli (7.2%), Iodamoeba buetschlii (0.7%), Entamoeba nana (3.8%), Entamoeba hartmanni (0.3%), Giardia lamblia (4.6%), Blastocystis hominis (2.6%), Trichomonas hominis (1.1%), Balantidium coli (0.01%). No significant difference was found between males (18.4%) and females (18.5%) ( P 0.05) . Nationality based infection rates were noted as 13.3% in Hans, and 14.4% in Tu, 22.1% in Zang, 23.7% in Hui, 27.7% in Menggu, and 53% in Sala minorities.