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.