Induction of anesthesia with inhalation of sevoflurane was evaluated in 45 patients. Inhalation anesthesia was induced by a single vital capacity breath followed by spontaneous breathing. The compositions of anesthetic gases were as follows: 5% sevoflurane in oxygen, 5% sevoflurane in 67% nitrous oxide and oxygen, and 7% sevoflurane in 67% nitrous oxide and oxygen. The time (mean +/- SEM) necessary for the loss of consciousness was 85 +/- 6, 56 +/- 4, and 42 +/- 3 seconds, and breathing frequency was 8 +/- 1, 5 +/- 0.6, 1.4 +/- 0.2, in each composition of anesthetic gasses, respectively. Changes in blood pressure and heart rate were relatively small. The technique was found to be acceptable to all of the patients studied. We conclude that the technique of single breath induction with sevoflurane is a safe and acceptable alternative to intravenous induction in cooperative adult patients.