The hypotheses of the study are: (1) a positive history of coagulopathy predicts a higher postoperative haemorrhage risk, (2) a positive laboratory screening for coagulopathy can forecast a higher haemorrhage risk and (3) the haemorrhage risk in patients with known bleeding disorder is elevated. In a multicentre study information on 3,041 tonsillectomies in adults over 9 months, from 1st October 2009 until 30th June 2010, was evaluated. The outcome variables were patient characteristics, postoperative haemorrhage, history of coagulopathy and laboratory screening for coagulopathy. A history of coagulopathy and laboratory screening for coagulopathy were performed in almost all patients (98.6 %, 2,998/3,041). The overall haemorrhage rate was 16 %, including all bleeding episodes after extubation, with 4.8 % returning to theatre. A positive history was reported in 2 % (55/3,041) and a positive laboratory screening in 3 % (94/3,041) of all patients. A positive history is significantly associated with a higher risk of postoperative haemorrhage (31 %, 17/55, p < 0.002) compared to patients with a negative history (16 %, 387/2,497). A positive laboratory for coagulopathy was not significantly associated with an increased haemorrhage risk (20 %, 19/94, p < 0.235) compared to patients with a negative laboratory (16 %, 390/2,249). The haemorrhage risk for adults with a bleeding disorder is twice as high (31 %, 17/55) as for adults without bleeding disorder (16 %, 476/2,973). In conclusion, an adult patient's history of coagulopathy should be taken prior to tonsillectomy as a positive history doubles the haemorrhage risk while a laboratory screening for coagulopathy has no significant power to predict an elevated haemorrhage risk. Bleeding disorders double the risk of postoperative haemorrhage. [ABSTRACT FROM AUTHOR]