We describe an unusual case of tumour lysis syndrome in a child with a high-grade lymphoma undergoing a staging laparotomy. The patient presented with a refractory ventricular arrhythmia, which required continuous resuscitation in the operating room and continuous venous-venous haemodialysis in the intensive care unit. This case report suggests that surgery is a possible trigger for developing tumour lysis syndrome, so anaesthetists should be alert to this possibility during surgery in patients with pre-existing high tumour burdens.