To compare the advantages and disadvantages of potassium titanyl phosphate laser with those of bipolar radiofrequency techniques, in paediatric tonsillectomy. Prospective, randomised, clinical study. From July 2004 to April 2006, 80 patients aged between 10 and 15 years, with tonsillectomy planned for chronic tonsillitis, were included in the study. Children were prospectively randomised into two equal groups: potassium titanyl phosphate laser tonsillectomy and bipolar radiofrequency tonsillectomy. Operative time and intra-operative blood loss were recorded. Patients were scheduled for follow up during the first, second and fourth post-operative weeks. They were asked to record their pain and discomfort on a standardised visual analogue scale, from zero (no pain) to 10 (severe pain). Post-operative complications were also recorded and managed. The potassium titanyl phosphate laser group showed a slightly longer operative time (mean 12 minutes) than the bipolar radiofrequency group (mean 10 minutes). Intra-operative blood loss was significantly less in the potassium titanyl phosphate laser group (mean 21 cm3) than in the bipolar radiofrequency group (mean 30 cm3). In the first week, post-operative pain scores were less in the potassium titanyl phosphate laser group than in the bipolar radiofrequency group (means 7.5 and 8.5, respectively). However, in the second week pain scores increased more in the potassium titanyl phosphate laser group than in the bipolar radiofrequency group (means 8.5 and 6, respectively). In the fourth week, both groups showed equal and nearly normal pain scores. No case of reactionary post-tonsillectomy haemorrhage was recorded in either group. Only one case of secondary post-tonsillectomy haemorrhage was recorded, in the potassium titanyl phosphate laser group (2.5 per cent), managed conservatively. Both the potassium titanyl phosphate and the bipolar radiofrequency techniques were safe and easy to use for tonsillectomy, with reduced operative time, blood loss and complication rates and better post-operative general patient condition. Potassium titanyl phosphate laser resulted in reduced operative bleeding and immediate post-operative pain, compared with the bipolar radiofrequency technique. However, potassium titanyl phosphate laser required slightly more operative time and caused more late post-operative pain than the bipolar radiofrequency technique. The low rate of recorded complications showed that both techniques cause little damage to the tonsillar bed during dissection, thus minimising complications.