The influence of new promising peptide (APCH3 and PT1) and nonpeptide analgesics (sevanol) on the behavior of male ICR mice was studied. All studied compounds at doses producing significant analgesic effects did not influence the behavior of mice in open-field tests. However, APCH at doses 10,000 times greater than the pharmacologically active dose produced sedative effects. Also, sevanol at a dose of 35 mg/kg caused statistically significant behavioral changes relative to the pharmacologically active dose (1 mg/kg) but not to the controls.