To evaluate the relationship between the development of retinopathy of prematurity (ROP) and neutrophil-to-lymphocyte ratio (NLR), lymphocyte-to-monocyte ratio (LMR), and platelet-to-lymphocyte ratio (PLR). The medical records of 153 preterm infants born before the 34th week of gestation, were retrospectively reviewed. Complete blood cell (CBC) and C-reactive protein (CRP) results measured within the first 24 h of life were recorded. NLR, LMR and PLR were calculated by dividing neutrophil count by lymphocyte count, lymphocyte count by monocyte count, and platelet count by lymphocyte count, respectively. Analysis of possible risk factors related with ROP development was evaluated using logistic regression analysis. Results were compared between infants with and without ROP. A total of 153 infants, of which 64 (41.9%) with ROP and 89 (58.1%) without ROP, were included in the study. While lymphocyte count and LMR were found to be significantly lower in infants with ROP (p = 0.015 and p = 0.044), neutrophil count and NLR were found to be significantly higher (p = 0.021 and p = 0.046, respectively). No significant difference were observed in platelet and monocyte count and PLR (p = 0.808, p = 0.170 and p = 0.075, respectively). Multivariate logistic regression analysis revealed that gestational age, birth weight and NLR were major risk factors for the development of ROP (OR:0.59; p = 0.01, OR:1.00; p = 0.02 and OR: 2.56; p = 0.02, respectively). This study supports that, in addition to prematurity, NLR on the first postnatal day has a significant predictive value in ROP.