Objective: To evaluate and compare the management and associated morbidity in inborn and outborn babies with meconium aspiration syndrome admitted to the Neonatal Intensive Care Unit and ventilated with high frequency oscillatory ventilation. Methods: A retrospective cohort study with a review of clinical data from newborns, admitted to the Neonatal Intensive Care Unit during a six-year period (from 1999 to 2004) and ventilated with early high frequency oscillatory ventilation, first intention in inborns and immediately after Neonatal Intensive Care Unit arrival in outborns. Rresults: In the present study, 27 newborns were included: 12 inborn and 15 outborn infants. Severity criteria were similar in both groups. The pulmonary morbidity associated was severe persistent pulmonary hypertension - 12 (seven outborns), pneumothorax - five (three outborns), interstitial emphysema – two (one outborn) and pulmonary hemorrhage – one outborn. Hypoxic-ischemic encephalopathy II-III occurred in six newborns (four outborns). The therapeutic procedures were surfactant administration in 22 newborns (13 outborns), nitric oxide in 12 newborns (7 outborns) and magnesium sulphate in four newborns (three outborns). The median length of ventilation was six days (inborn infants: four and half days; outborn infants: ten days) and the median length of oxygenation supply was ten days (inborn infants: four and half days; outborn infants: 15 days). The median length of stay was 13 days (inborn infants: 11 days; outborn infants: 16 days). One outborn infant died. Cconclusions: With this ventilation strategy, we have found no significant statistical differences between the two newborn groups, except for the length of oxygenation supply that was longer in the Outborn Group.