The objective of this study is evaluate the pulmonary function in full term newborn infants, comparing classic with non invasive techniques. We describe the pulmonary function laboratory and software developed at Instituto Fernandes Figueira. We studied 10 healthy full-term newborn infants (birth weight 3.260g + - 460g) Occlusions were performed at inspiration end and during expiration which allowed us to calculate values for total pulmonary resistance (TPR) and total pulmonary compliance (TPC). Esophageal pressure was measured with a water filled catheter positioned in the lower third of the easophagus, to obtain lung resistance (RL) and compliance (CL). All signals were digitized at 60 Hz into a microcomputer for further analysis. Mean results of our study are: CL= 1,78 + - 0,36 ml/cm H2O/kg, TPC= 1,12 + - 0,27 ml/cmH2O/kg and TPR= 16 + - 4 cmH2O/l/seg/kg. Our values are very similar to the ones in the current literature.