Forty-seven patients undergoing cystoscopy received etomidate with either fentanyl or alfentanil to induce and maintain anaesthesia in a randomized, double-blind comparison. There were no significant differences in the composition of the groups, or in the clinical efficacy and side-effects of the anaesthetic combinations used. Early recovery of consciousness and orientation was similar in both groups, but late recovery, assessed by use of Maddox Wing and digit substitution tests, was faster in the patients who received alfentanil.