65 children were analysed prospectively before and after adeno-tonsillectomy to determine the incidence of upper airway infections, snoring and nocturnal obstructive symptoms. The weight and height percentiles were also determined before and after adeno-tonsillectomy. The Oxygen Desaturation Index (ODI) was measured in 27 children suspected of having a sleep apnea syndrome. In six of these children polysomnographic studies were carried out. A statistically significant reduction (p < 0,005) of upper airway infections could be seen six to twelve months after adeno-tonsillectomy. In 25 children (38%), we observed a postoperative weight gain and in eight cases (12%) a height gain. The obstructive symptoms, especially snoring and respiratory apneas, disappeared or were significantly reduced in 90% of the cases after adeno-tonsillectomy. All preoperatively pathological ODI and AHI normalised after the operation (p < 0,005).