Clinical usefulness of rapid inhalation induction of anesthesia (RII) using 5.0 vol.% isoflurane (GOI) and sevoflurane (GOS) with N2O was evaluated in 124 canine patients. Induction times, loss of various reflexes and movement times were significantly faster in GOI group than in GOS group. Scores for the easiness of intubation and the degree of movements were also significantly less in GOI group than in GOS group. Positive correlation between body weight and degree of movements was observed in both induction groups. Thus, RII using GOI is a practically useful and safe induction modality in small- to medium-sized dogs.