A survey on the prevalence of intestinal protozoan cysts was conductcd in Jeonlanam Do (Province), Korea in 1981. A total of 4,116 specimens was collected from 2,035 male and 2,086 female inhabitants in 4 urban and 7 rural areas. Each case was selected randomly to represent 1,000 inhabitants referred to the census in 1980. Formalin-Ether sedimentation technique was employed to concentrate the cysts and one Lugol's iodine stained smear was examined for each case. The results were summarized as follows: 1. The cases who passed out protozoan cysts of any kind were 9.1 % out of total 4,116 examined, and cumulative positive rate was 11.0 %. Among the positive cases, 16.5 % were infected by two or more species of protozoa. 2. Total 5 species of cysts were detected and the positive rates were as follows; Entamoeba histolytica 1.4 %, E. Coli, 4.9 %, Endolimax nana 2.5 %, Iodamoeba butschlii 0.4 % and Giardia lamblia 1.9 %. 3. The cyst positive rates varied greatly by the surveyed area. The positive rate in rural area was 11.6 % compared with 5.7 % in urban area. The highest rate was found 14.5 % in Gurye Gun (County) and the lowest 3.6 % in Mogpo Si (City). 4. Female showed much higher positive rate than male as 11.8 % compared with 6.4 % and the cumulative rate 14.2 % and 7.6 % respectively. By age group, the rate was highest as 13.9 % in 40~49 years and next 12.5 % in over 60 years group. The cyst prevalence rate diminished remarkably in Jeonlanam Do compared to previous records. However, the finding that 20.2 % of females of 40 years were the carrier of protozoan cysts was an important information in public health point of view.