The purpose of this study was to re-evaluate cutoff values used in screening for retinopathy of prematurity (ROP) in Croatia and to propose postnatal weight gain as an additional criterion, based on the Colorado Retinopathy of Prematurity prediction model. Medical records of 267 premature infants from the Zagreb University Hospital Centre that underwent ROP screening between January 2009 and December 2010 were reviewed retrospectively. Collected data included gestational age, birth weight, sex, weekly weight measurements and fundus examination records. Results showed the cutoff values of gestational age (GA) and birth weight (BW) used in Croatia to be appropriate and postnatal weight gain in the first 28 days could be used as an additional criterion on screening in the following way: net weight gain in the first 28 days of ≤932 g for prediction of any form of ROP and of ≤660 g for prediction of severe ROP should be added to the existing criteria of GA (≤32 weeks) and/or BW (≤1500 g). Infants with a non-physiological postnatal weight gain are exception. This is the first Croatian study to propose postnatal weight gain as an additional criterion on ROP screening and requires further validation on a larger sample of Croatian infants.