To assess the effect of paliperidone extended-release (ER) tablets in patients with acute symptoms who had previously received risperidone. Data for this post-hoc analysis were pooled from three 6-week, double-blind, placebo-controlled trials in patients treated with paliperidone ER 3–12 mg/day or placebo. Patients had to have received risperidone for ≥4 weeks within 2 weeks of study entry. Assessments were done using the Positive and Negative Syndrome Scale, Clinical Global Impressions–Severity scale, Personal and Social Performance scale, the Simpson–Angus Scale , and adverse event (AE) reports. Altogether, 198 patients (paliperidone ER, n=142; placebo, n=56) met the established criteria. Mean (SD) duration of prior risperidone treatment and dose were 418.8 (572.8) days and 4.4 (2.5) mg/day for paliperidone ER and 527.0 (805.3) days and 4.1 (2.5) mg/day for placebo. Study completion rates were 61.3% for paliperidone ER versus 42.9% for placebo. At endpoint, paliperidone ER showed significant improvement versus placebo (P<0.05) in Positive and Negative Syndrome Scale, Clinical Global Impressions–Severity, and Personal and Social Performance scores. Mean baseline Simpson–Angus Scale scores were low, with no significant changes at endpoint in either group. AEs ≥10% with paliperidone ER versus placebo were headache (16.2 vs. 16.1%), insomnia (14.1 vs. 16.1%), and agitation (8.5 vs. 10.7%). AE-related discontinuations were 2.1% with paliperidone ER and 5.4% with placebo. In patients who had received risperidone previously but remained sufficiently symptomatic for enrollment, paliperidone ER was significantly more effective than placebo in reducing symptoms and producing functional gains.