Forty children (age group four to 12 years) undergoing adenoidectomy and/or tonsillectomy were subjected to pre- and post-operative polysomnography. Thorough clinical evaluation and X-ray soft tissue nasopharynx lateral view was carried out for all the patients. The tonsils were clinically graded from grade I to IV, whereas the adenoids were measured radiographically (using three different measurements) in all children. Thirty out of 40 (75 per cent) children presented with predominant obstructive symptoms, out of whom 22 (73.3 per cent) were found to have obstructive sleep apnoea (OSA), i.e. apnoea index > five per hour. The remaining 10 (25 per cent) had predominantly inflammatory symptoms on presentation and out of these two (20 per cent) were found to have OSA. Relative adenoid size expressed as a ratio between the distance from the point of maximum thickness of adenoids along a line drawn along a straight part of the basiocciput and distance from the posterior nasal spine to the antero-inferior edge of the spheno-basioccipital synchondrosis, was found to have a highly significant correlation with the grade of OSA. In our study, all patients with this ratio greater than 0.64 were found to have OSA. No correlation between tonsil size and grade of OSA was found. There was a highly significant improvement in polysomnographic scores following surgery in all patients.