We investigated whether pretreatment with agmatine affected methamphetamine (METH)-induced stereotypy and hyperlocomotion in male ICR mice. Agmatine pretreatment alone had no effects on locomotion or stereotypy. Pretreatment of mice with agmatine produced a dose-dependent attenuation of locomotion induced by low dose of METH. Similarly, agmatine pretreatment produced a dose-dependent attenuation of the total incidence of stereotypical behavior induced by a low dose of METH (5 mg/kg). The stereotypy induced by this dose was predominantly characterized by stereotypical sniffing. By contrast, agmatine did not affect the total incidence of stereotypy induced by a higher dose of METH (10 mg/kg). However, the nature of the stereotypy induced by this dose of METH was substantially altered: stereotypical biting was significantly reduced by agmatine pretreatment, while stereotypical sniffing and persistent locomotion were significantly increased by pretreatment with agmatine. Agmatine pretreatment appears to produce a rightward shift in the dose-response curve for METH. This data suggest that the antagonism of METH effects by agmatine should be investigated as a potential treatment for METH addiction or METH overdose.