The benzodiazepine anxiolytic diazepam did not affect immobilization-elicited hyperglycemia, although a high dose increased blood glucose levels in normal mice. The serotonergic anxiolytic tandospirone reduced immobilization-induced hyperglycemia dose-dependently, Hyperglycemia elicited by immobilization stress was completely prevented by adrenalectomy but not by pretreatment with the corticosterone synthesis inhibitor dexamethasone. These results suggest that the effects of two anxiolytics, diazepam and tandospirone, on immobilization stress-induced hyperglycemia are quite different, although both drugs reduce anxiety. Furthermore, our results indicate that immobilization stress-elevated hyperglycemia is closely related to adrenaline release from the adrenal gland and that tandospirone may inhibit stress-induced hyperglycemia by modifying this mechanism.