PURPOSE: To report refractive changes after cataract surgery and intraocular lens implantation in infants and children. METHODS: In an ongoing prospective study, the refractive errors of all patients younger than 18 years undergoing intraocular lens implantation were determined at 6 weeks, 3 months, 6 months, and 1 year, and at least yearly thereafter. All patients with greater than 6 months of follow-up were included in the study. RESULTS: Eighty-three eyes of 81 patients were identified. Cataracts were traumatic in 32 eyes (38%) and developmental in 42 eyes (50%). At implantation, the mean (+/-SD) age was 6.3 +/- 4.6 years (range, 9 months to 17 years). The mean follow-up was 26.6 months (range, 6 months to 6.6 years). Patients 0 to 2 years old at the time of implantation demonstrated a mean myopic shift of -3.00 diopters during a mean follow-up period of 2.5 years. Patients 2 to 6 years old at the time of implantation demonstrated a mean myopic shift of -1.50 diopters in a similar follow-up period. Children aged 6 to 8 years experienced a mean myopic shift of -1.80 diopters during a mean follow-up period of 3.0 years, while children older than 8 years at the time of intraocular lens implantation experienced a mean myopic shift of -0.38 diopters during a mean follow-up period of 1.8 years. On average, the operated-on eye showed a greater mean myopic shift than the fellow eye. No statistically significant differences in refractive change were found in comparing amblyopic to nonamblyopic eyes, traumatic to nontraumatic cataracts, or primary to secondary intraocular lenses. CONCLUSIONS: Our data demonstrate a trend toward increasing postoperative myopia in pediatric patients undergoing intraocular lens implantation. This myopic shift is greatest in the younger age groups and persists until at least 8 years of age. There is much variability in the postoperative refractive changes, and predicting exactly when and where the refraction will stabilize for an individual patient is difficult.