The effects of flurazepam (0.0, 0.5, and 3.0 mg/kg) on methylphenidate-induced increases in stereotypy, gnawing, sniffing, and locomotion were evaluated in Swiss-Webster mice in daytime and nighttime experiments. Methylphenidate (50 mg/kg) increased overall stereotypy and stereotyped gnawing behavior; two doses of methylphenidate (25 mg/kg and 50 mg/kg) increased locomotion and sniffing behavior. Flurazepam 3.0 mg/kg augmented methylphenidate-induced stereotyped gnawing behavior and stereotypy. Flurazepam significantly decreased locomotion and sniffing, but did not interact with methylphenidate's effects on locomotion and sniffing.