The effects of intracerebroventricular (i.c.v.) pretreatment with the noradrenergic neurotoxin DSP-4 and β 1- and β 2-adrenoceptor antagonists on the expression of morphine withdrawal signs were investigated in mice. Mice were chronically treated with morphine (8–45 mg/kg, s.c.). Several withdrawal signs were observed following naloxone challenge in morphine-dependent mice which had been pretreated with vehicle. Treatment with DSP-4 before the naloxene chalenge suppressed the expression of morphine withdrawal signs, including jumping and “wet dog” shakes. Similarly, pretreatment with the β 1-antagonist atenolol significantly reduced the incidence of naloxene-precipitated jumping and “wet dog” shakes. However, pretreatment with the β 2-antagonist ICI118,551 suppressed the expression of “wet dog” shakes, but not that of jumping. These findings suggest that the central noradrenergic system may mediate the expression of withdrawal signs. The blocking effects of β-antagonists indicate that naloxone-precipitated jumping may be mediated predominantly by β 1-adrenoceptors, while naloxone-precipitated “wet dog” shakes may be mediated by both β 1- and β 2-adrenoceptors.