Background: The benefits of hypothermia on neurodevelopment of newborns ≥ 36 weeks gestation with hypoxicischemic encephalopathy have been shown in large clinical trials. The security of hypothermia in premature infants ≤ 36 weeks has not been rigorously evaluated, although its feasibility has been suggested in recent studies. The present study aims: 1) To describe extraneural involvement in infants 33-35 weeks gestation with severe hypoxicischemic encephalopathy treated with hypothermia 2) To compare organ dysfunction with infants ≥ 36 weeks gestation. Methods: Retrospective observational study of prospective data collected. Consecutive newborns of 33-35 weeks gestation, ≥ 1800g birth weight and severe hypoxic-ischemic encephalopathy were included. Data were compared with a cohort of newborn infants ≥ 36 weeks with severe encephalopathy. Twenty clinical and laboratory variables of 6 organ-systems (cardiovascular, respiratory, renal, haematological, hepatic and pH and electrolytic imbalance) were studied and a multiorgan dysfunction scale was applied daily during the first 3 days of life. Results: Eight preterm newbors with severe HIE were compared with 31 term neonates with severe HIE. All infants presented with moderate-to-severe organ injury. There were no differences in most of organ variables, the number of affected organ-systems or the scores in the Multiorgan dysfunction Scale between both gestational age groups in the first 3 days of life (p>0.05). Conclusion: Organ injury in infants of 33-35 weeks gestation with severe HIE evaluated for hypothermia is not more severe regarding newborns ≥ 36 weeks gestation. Therapeutic hypothermia appears feasible in this gestational age group although clinical trials are needed to answer this question.