The clinical manifestations in filarial infection were examined during 1965-1966 from the known endemic areas: Yongju, a mountainous inland area and Cheju-Do, an island. 1. All the microfilaria which were found during the survey were Brugia malayi. 2. The principal symptom was cuticular hypertrophy (elephantiasis). It was found in 4 cases from Yongju among 707 villagers, 84 cases from Cheju-Do among 2,376 villagers. 3. Four microfilaremia cases (4.5%) were found among a total of 88 cases of elephantiasis. 4. In Cheju-Do, the higher incidence of elephantiasis was observed among people over 20 years old and the females showed much higher incidence than males (30 males and 54 females). 5. The cuticular hypertrophic changes (elephantiasis) appeared more often in the lower extremities(77%) than in the upper part of the body, and in the right side than in the left.