Eighteen children with tonsillar hypertrophy and signs of upper respiratory obstruction during sleep have been treated by cryosurgery. Nitrous oxide has been used as the refrigerent and the freezing time has been 3 minutes X 2 on each tonsil, with spontaneous thawing in between. All the children had earlier undergone adenoidectomy without relief on their symptoms. Fourteen children are free of obstruction two years after treatment, 12 after one treatment and two after two treatments. The treatment has been found to be free from complications. Cryosurgery represents an alternative to conventional tonsillectomy in the treatment of upper respiratory obstruction caused by enlarged tonsils in children.