Pregnanolone emulsion was administered i.v. to 13 healthy male volunteers to assess its potential as an agent for i.v. induction of general anaesthesia and to establish a pharmacokinetic profile at two doses. Each subject received 0.5 mg kg-1, 0.75 mg kg-1 and 1.0 mg kg-1 on successive occasions, the rate of administration being constant for each dose. Pregnanolone emulsion was found to produce smooth and reliable induction of general anaesthesia with cardiorespiratory effects comparable to those of other i.v. induction agents.