This study assessed the efficacy and the safety of a dosing regimen that was revised from earlier studies for the investigational injectable atypical antipsychotic paliperidone palmitate (approved in the USA, August 2009) for adult patients with acutely exacerbated schizophrenia. The patients (N = 652) were randomly assigned (1:1:1:1) to paliperidone palmitate at 25, 100, or 150 mg eq. or placebo in this 13-week double-blind study. The patients received an injection of paliperidone palmitate at 150 mg eq. or placebo in the deltoid muscle on day 1 and the assigned fixed dose or placebo in the deltoid or gluteal [corrected] on day 8 and then once monthly (days 36 and 64). No oral supplementation was used. Target plasma levels were achieved by day 8 in all paliperidone palmitate groups. The mean change in Positive and Negative Syndrome Scale total score from baseline to end point improved significantly (P < or = 0.034) in all the paliperidone palmitate dose-groups versus placebo. Paliperidone palmitate treatment with this revised dosing regimen led to the achievement of rapid and consistent therapeutically effective plasma levels that were maintained by once-monthly dosing in either the deltoid or gluteal muscle. Common treatment-emergent adverse events (> or =2% of patients in any of the treatment groups) that occurred more frequently in the total paliperidone palmitate group versus the placebo group (with > or =1% difference) were injection-site pain (7.6% vs 3.7%), dizziness (2.5% vs 1.2%), sedation (2.3% vs 0.6%), pain in the extremity (1.6% vs 0.0%), and myalgia (1.0% vs 0.0%). The paliperidone palmitate treatment was efficacious and generally tolerated across the dose range (25, 100, or 150 mg eq.) in adult patients with acutely exacerbated schizophrenia.