Background: Retinopathy of prematurity (ROP) is disorder of developing retinal blood vessels in premature infant retina. Several risk factors are associated with development of ROP.We aimed to assess whether poor postnatal weight gain is significant predictor for development of ROP. Objectives: To assess postnatal weight gain alone as predictor of ROP and to co relate other risk factors and poor postnatal weight gain as a predictor of ROP. Methodology: Prospective observational study was conducted on 101 preterm neonates ≤34 weeks and ≤ 2000g admitted to Level III Neonatal intensive care unit (NICU) of tertiary referral Medical College Hospital in Central Karnataka ,South India and fitting into inclusion criteria from 1st February 2021 to 31st November 2022.All neonates were screened for ROP at eligible postmenstrual age as per national guidelines and early morning, prefeed, nude weight of the baby and weekly postnatal weight gain were recorded.ROP was done using RetCam by ophthalmic technician and reported by ophthalmologist remotely.Data was collected and co related with ROP diagnosis using logistic regression.Results: Of 101 neonates, 18 of them developed ROP. Preterm neonates with ROP had significantly lower mean relative weight gain (41.5± 3.5g) than neonates without ROP(87± 2.8 g) ,p<0.001.In our study 17 out of 18 neonates who developed ROP had mean weekly weight gain of <100 g (p=0.02).Relative weekly weight gain < 100 g was associated with higher risk of developing ROP with odds ratio of 0.94.Logistic regression model with risk factors, non-administration of antenatal corticosteroids to mother ,gestational age, birth weight, prolonged oxygen therapy and low weekly weight gain < 100 g was statistically significant and explained 43 % variance in ROP development, correctly classifying 88.1 % cases.Conclusion: We can conclude that poor postnatal weekly weight gain < 100g is significant risk factor and useful predictor for development of ROP.