The effect of continuous propofol administration on creatine kinase and suxamethonium-induced postoperative myalgia was evaluated in 50 patients randomised into two groups of 25 patients each. Induction of anaesthesia was identical in all patients. Anaesthesia was maintained with 66% nitrous oxide in oxygen supplemented by either isoflurane 1% or continuous propofol. Creatine kinase was measured before and after operation. Myalgia was evaluated postoperatively by a blinded observer. The median level of myalgia was reduced significantly in the continuous propofol group (p = 0.011). The median creatine kinase value increased significantly in the isoflurane group (from 90 to 160 IU, p = 0.001).