Tonsillectomy is a common otolaryngological procedure and is associated with a small risk of postoperative pharyngeal haemorrhage. This study compares secondary post tonsillectomy haemorrhage rates between two operative techniques: diathermy tonsillectomy and diathermy tonsillectomy with tonsillar bed oversew. A total of 424 patients underwent tonsillectomies with or without other procedures such as adenoidectomy and grommet insertion by two ears, nose and throat surgeons at three hospitals from May 2012 to July 2013. A diathermy tonsillectomy was performed in 266 patients, while a diathermy tonsillectomy with tonsillar bed oversew was performed in 158 patients. All patients were followed up within 2-4 weeks of surgery. Primary haemorrhage did not occur in either surgical technique groups. Secondary haemorrhage occurred in 20 patients (7.52 %) in the diathermy tonsillectomy group and in 9 patients (5.70 %) in the diathermy with tonsillar bed oversew group. This result was not significantly different (OR = 0.74, 95 % CI 0.33-1.67, p = 0.47). Sex, age, indication for surgery and whether or not a tonsillectomy was performed alone or with other procedures were not significant factors for secondary haemorrhage. In summary, routine tonsillar bed oversew after diathermy tonsillectomy does not reduce the risk of secondary tonsillar haemorrhage.