Among 666 premature infants or low birthweight infants who were admitted in NICU of St. Francisco General Hospital from January 1990 to Jun 1992, 96 infants were diagnosed as retinopathy of prematurity by indirect ophthalmoscope. The result were follows: 1) Among 666 patients, retinopathy of prematurity developed in 96 patients(14.1%) 2) The high incidence was observed in low birthweight and small gestational age. 3) Mean age of first diagnosing time was 42.0( 12 day of life and mean gestational age was 31.8 2.5 weeks and mean birthweight was 1646.5 (350.7gm. 4) In gestational age, birthweight and duration of oxygen therapy, there was statistically difference between cryotherapy group and spontaneous regression group. Other possible risk factors-hyaline membrane disease, apnea, anemia-were showed higher incidence in cryotherapy group. 5) Among the 20 infants who were treated with cryotherapy, 16 infants (80%) showed regression of neovascularization.