Tonsillectomy is one of the most frequently performed surgical procedures in children and is associated with a relatively high risk of postoperative complications. The question often arises whether paediatric obstructive sleep apnoea should be diagnosed with preoperative sleep testing and whether preoperative coagulation tests should be performed in every child undergoing tonsillectomy. In order to answer these questions, the relevant German and English literature was analysed. Adenotonsillectomy in childhood usually resolves the underlying sleep-related breathing disorder. Nevertheless, especially in children with clinical risk factors such as severe sleep apnoea, obesity or craniofacial malformation, respiratory complications should be expected in the postoperative phase. Routine sleep tests prior to tonsillectomy are neither necessary nor practical for preoperative evaluation. Inherited coagulation disorders have only a limited effect on the occurrence of postoperative bleeding and the predictive value of routine coagulation tests is limited. As long as a thorough clinical history is negative, routine coagulation tests are not helpful or necessary prior to tonsillectomy in children.