Prepulse inhibition (PPI) of the acoustic startle response (ASR) was disrupted by systemic administration of apomorphine (APO) (2 mg/kg, i.p.). Microinfusion of the selective adenosine A2a-recceptor agonist CGS21680 (0.05 microgram in 1.0 microliter per side) into the nucleus accumbens (NAc), had no significant effect in animals with systemic vehicle pretreatment, but significantly reversed the disruption of PPI in rats pretreated with APO. Adenosine is, therefore, involved in the control of PPI through its actions on A2a receptors in the NAc. APO-induced disruption of PPI is considered to represent an animal model useful for screening both typical and atypical antipsychotic agents. The present results add further support to the view that A2a-receptor agonists may be potentially useful antipsychotic agents.