The effect of oro-naso-pharyngeal suction at birth on pulmonary mechanics is described in a random assigned controlled study of 40 normal term vaginally born infants. Twenty cases had their oro-naso-pharynx suctioned immediately after birth (S Group), whereas 20 were not suctioned in the neonatal period (NS Group). A computerized pneumotachographic system (MECVENT) was used for the assessment of respiratory mechanics (Dynamic Compliance (C. Dyn.) and Total Pulmonary Resistance (R) in inspiration and expiration at 10, 30 and 120 minutes after birth. In both groups the C. Dyn increased during the study period whereas the R decreased, mainly in the initial 30 minutes. No significant differences were observed between S and NS groups for any of the parameters of respiratory mechanics. The results obtained in this study provide no physiological basis to recommend routine airway suction at birth in normal, term, vaginally born infants.