The maximum inspiratory force (MIF) that children and adults can generate has been shown to be one of the parameters that correlates positively with their ability to be weaned from mechanical ventilation. The purpose of this study was to determine if the MIF might also be useful in judging the ability of neonates to be weaned from mechanical ventilation.The relationships among MIF, PaCO2, spontaneous respiratory rate (SRR), and patient outcome were studied in 20 neonates receiving ventilator support (babybird). A Boehringer inspiratory force meter was used to obtain MIF daily and just before extubation. At each measurement, the patient was given 3–4 trials to achieve MIF with 6 inspiratory attempts during airway occlusion. An attempt was made always to occlude the airway at FRC. Two variable regressions with a level of significance ofp< 0.05 showed: (1) MIF did not correlate with PaCO2or SRR, or change significantly on a daily basis to the value at the time of extubation in the entire group or when the patients were compared by gestational age; (2) MIF did not correlate with reintubation (N = 4, mean 29 ± 13 cm H2O) versus no reintubation (N = 16, mean 33 ± 15 cm H2O). This lack of correlation may be due to the timing difficulties of occluding the infant airway exactly at FRC. The timing difficulties in neonates are caused by a rapid respiration rate (l/sec), small tidal volume (5–20 ml), irregular respiratory pattern, and paradoxical chest movement.