This is a prospective incidence study of 250 secondary post-tonsillectomy haemorrhages from a population of 2706 tonsillectomies performed over a seven-year period, which aims to ascertain the incidence and character of post-tonsillectomy secondary haemorrhage. Out of 250 post-tonsillectomy secondary bleeds (9.2 per cent of total; 95 per cent CI = 8.2 per cent – 10.4 per cent), 39 patients had a severe bleed (1.4 per cent; 95 per cent CI = 1.2 per cent – 2.1 per cent). The incidence of secondary tonsillectomy haemorrhage increased with age, peaking at 30–34 years in both men and women (p < 0.001), with no statistically significant difference between the two sexes (p = 0.23). The incidence of serious haemorrhage increases in the older age categories (p = 0.005) but is not influenced by gender (p = 0.50). The majority of secondary tonsillectomy haemorrhages presented between the fourth and seventh day post-operation (69.8 per cent). These results now provide the basis for informed consent for a tonsillectomy in our department.