In pursuit of β-hCG change following hydatidiform moles treated from July, 1982 to April, 1984 at the department of Obstetrics and Gynecology, Medical School, Chon-buk National University, maternal age, parity, degree of maturation of molar tissue, size of uterus, gestaional weeks, initial β-hCG levels, presence of theca lutein cyst, and initial treatment method(sucion curettage or hysterectomy) were taken into consideration as possible prognostic factors, resulting in followings. 1. The frequency of molar pregnancy was one per 44 deliveries in the same period of this study. 2. The mean initial β-hCG level of 40 patients was 72,958.7mIU/ml and the mean duration (days) until undetectable β-hCG level (below 5mIU/ml) was 76.1 days. 3. The regression of β-hCG titer in the group of old age(over 40 years old), high parity(above 4), classical mole, large for gestational age, high initial β-hCG level (over 100,000mIU/ml) and theca lutein cyst was prolonged. 4. In relation to the gestational weeks and initial treatment method(suction curettage or hysterectomy), there were no significant differences in β-hCG titer regression. 5. All 40 patients whose β-hCG declined progressively to the undectable levels have remained well and got rid of disease in one-year follow-up evaluation.