Sixteen rats, separate from those used for self-administration, were evaluate for rotorod performance. Two-way rmANOVA revealed a Treatment effect (F(4,75)=9.91), Time effect (F(4,300)=21.74), and Treatment x Time interaction (F(16,300)=2.44). Mirtazapine had no effect on rotorod performance at any dose tested. The positive control, 10 mg/kg ip pentobarbital significantly impairment of rotorod performance across all time points tested (**p<0.01; Newman-Keuls post hoc).