Two hundred and fifty women undergoing termination of pregnancy during the first trimester under general anaesthesia were studied to determine the effects of precurarisation on suxamethonium-induced postoperative myalgia and on the need for postoperative analgesics after suxamethonium. Either alcuronium (0.03 mg/kg), atracurium (0.04 mg/kg), tubocurarine (0.05 mg/kg), vecuronium (0.01 mg/kg) or saline was administered in a double-blind manner 4 min before giving suxamethonium. An additional 50 patients were studied who received isoflurane rather than precurarisation and suxamethonium. Every pretreatment prevented fasciculations better than did saline (P less than 0.001). In the saline group, 92% of patients had fasciculations and in the other groups this ranged from 8 to 32%, respectively. On the first postoperative day, 76% of the patients in the saline group had myalgia while myalgia was manifested in 28, 54 and 34% of patients given alcuronium, tubocurarine or vecuronium, respectively (P less than 0.05). Atracurium failed in this effect with 62% having myalgia. In the isoflurane group, none of the patients complained of myalgia on the first postoperative morning. The need for analgesics was less (P less than 0.005) in the isoflurane group (8%) and in the pretreatment groups (18-27%) than in the saline group (42%). It is concluded that precurarisation with tubocurarine, vecuronium or, most effectively, with alcuronium but not with atracurium decreases suxamethonium-induced postoperative myalgia and seems to be necessary also during the first trimester of pregnancy.