PURPOSE: To develop a model for predicting postoperative keratometry in children undergoing cataract surgery with primary intraocular lens (IOL) implantation. METHODS: The longitudinal retrospective study included all children who underwent bilateral cataract surgery and had available intraoperative and postoperative keratometry data. Variables that could influence postoperative keratometry were analyzed, and a generalized estimating equation regression model was used to predict postoperative keratometry. RESULTS: One hundred twenty eyes of 60 children were included. The mean age at surgery was 2.95 ± 2.78 years (range: 0.12 to 10.95 years), the mean age at the last follow-up was 7.25 ± 4.61 years (range: 0.50 to 20.41 years), and the mean follow-up was 2.40 ± 2.33 years (range: 0.25 to 10.37 years). Keratometry measurements were obtained in both eyes during 510 postoperative visits. The mean keratometry values before surgery and at the last follow-up were 45.32 ± 2.57 diopters (D) (range: 40.75 to 53.88 D) and 44.62 ± 2.25 D (range: 40.63 to 51.25 D), respectively. Preoperative mean keratometry, age at cataract surgery, and age at follow-up were statistically significant predictors of postoperative keratometry. The model to predict postoperative keratometry = 3.1304 + 0.9388 × (baseline keratometry) + 1.8294 × Log10 (baseline age), -1.1336 × Log10 (age at follow-up), -0.7045 × Log10 (baseline age) × Log10 (age at follow-up) was determined. The correlation between measured and estimated keratometry was CONCLUSIONS: The model is a good predictor for future keratometry after bilateral pediatric cataract surgery with an IOL implant.