Forty eyes in twenty-two cases in the active phase of retinopathy of prematurity were treated with laser photocagulation. Thiry (93.7%) of the 32 eyes in type I and intermediate type were found in the cicartrical phase grade 1. In type Ⅱ in which cryocautery was used as combination therapy, only 2 eyes (25.0%) were found in grade 1, 2 eyes (25.0%) in grade 2, 1 eye (12.5%) in grade 4 and 3 eyes (37.5%) in grade 5. All 21 eyes in which photocoagulation was performed up to the middle of stage 3 were found in grade 1 (100%). However, among 11 eyes in which photocoagulation were performed in late stage 3, 9 eys (81.8%) were found in grade 1, and 2 eyes (18.2%) in grade 2. In conclusion, if adequate laser photocoagulation is performed in avascular ares at the middle of stage 3 of type Ⅰ and intermediate type, treatment in cicartrical phase grade 1 is possible. Laser photocoagulation is clearly more effective than the xenon are photocoagula-tion or cryocautery. However, in type Ⅱ it is difficult to control the condition by photocagulation alone, and early diagnosis followed by combination therapy using cryocautery is reqired.