SummaryThe incidence, severity and duration of early postoperative hypoxaemia were determined in 420 healthy infants and children undergoing elective plastic surgery. Mean value of preoperativeSpo2was 98.3 ± 0.87%. However, it decreased significantly to 92.7 ± 4.01% immediately following anaesthesia in the postanaesthesia recovery room (PAR) when children breathed room air. ThenSpo2gradually increased to 93.8 ± 4.25% at 10 min, 95.4 ± 3.14% at 30 min, 96.6 ± 2.25% at 60 min, 96.9 ± 1.69% at 120 min, and 97.4 ± 1.55% at 180 min, respectively. The incidence of hypoxaemia and severe hypoxaemia, which were 14.8% and 6.2% respectively on arrival in the PAR, decreased significantly to 6.6% and 1.9%, 30 min later. The hypoxaemia occurred most commonly within 1 h, particularly the first 30 min following anaesthesia. The hypoxaemia was more common and more severe in children undergoing cleft palate repair than other kinds of plastic surgery. A significant correlation was found between lowSpo2levels on admission to the PAR and children's age, fentanyl doses, and the infants’ recove