Objetive: To determine risk factors associated to retinopathy of prematurity (ROP) among premature infants. Method: Case control study. 31 new born infants with ROP and 62 control infants were evaluated neonatal factors. We studied infants with gestational age < 37 weeks from January 2010 to December 2011. Results: Mean birth weight was 1647 gr. And mean gestational age was 33.8 weeks. The incidence of ROP was 11.8 % in infants with gestational ages:32 weeks and 18.3% fur infants with birth weight < 1500 g. In multivariate logistic regression analysis the significant factors (p < O.OS) associated to ROP were gestational age (OR= 6.27), birth weight(OR=5.(6), pneumonia (OR= 6.42), neonatal asphyxia (OR= 4.75), neonatal hyaline membrane (OR -= 8.74), blood transfusion (OR - 18.49) and mechanical ventilation (OR - 13.63). Conclusion: Low birth weight, low gestational age, blood transfusion, mechanical ventilation and pneumonia, neonatal asphyxia and neonatal hyaline membrane are the main risk factors for the development of ROP.