In addition to differing in ethanol sensitivity, long-sleep (LS) and short-sleep (SS) mice also differ in response to GABAergic agents. In the present study the sensitivity of LS and SS mice to the anesthetic, hypothermic and anticonvulsant effects of benzodiazepine, flurazepam, was determined. Flurazepam (75-300 mg/kg) induced a dose-dependent loss of righting response in both lines. The LS line displayed a two-fold greater sensitivity to the anesthetic effects of flurazepam. A dose-dependent decrease in body temperature was also observed following administration of flurazepam (25-150 mg/kg), but the two lines did not differ on this measure. Determination of the anticonvulsant effects of flurazepam (1-6 mg/kg) against seizures induced by 3-mercaptopropionic acid revealed that the SS line was more sensitive to the anticonvulsant effects of this benzodiazepine. These studies demonstrate that LS and SS mice differ in response to flurazepam, but the nature of the difference depends on the type of response measured and the dose of flurazepam employed.