Two cases are reported of upper limb rhabdomyolysis occurring after prolonged ENT cancer surgery, the patient being part of the time in the right lateral position, with the left forearm outstretched. Surgery consisted of a vertical hemilaryngectomy with immediate parascapular free graft reconstruction in a 48-year-old man (10 h of surgery, with 6 h in a lateral position) and the surgical removal of a neoplasm involving the mouth floor and larynx in a 62-year-old man including parascapsular free graft reconstruction (10 h of surgery, with 7 h in a lateral position). In the early postoperative period, the patients complained of severe pain in the left forearm. There was a tense painful swelling of the forearm, combined with an increase in creatinine kinase plasma concentration, and myoglobinaemia. The mechanism involved was most likely a compression of the forearm muscles, together with prolonged surgery and the patient position. The part played by the state of the patients is discussed. Diagnosis must be made as soon as possible, as the only efficient treatment consists of an early fasciotomy together with the administration of alkali to avoid renal failure.