BACKGROUND: Risperidone is one of the atypical antipsychotic drugs that have effectiveness in the management of a range of psychiatric illnesses. Orally disintegrating (OD) formulations of risperidone that rapidly dissolve in the mouth, prior to swallowing without water have been developed to overcome any problems related to swallowing and improve acceptability. The goal of this study was to evaluate the bioequivalence of Risperdal OD(R) tablet 1mg and Quicklet(R) tablet 1mg. METHODS: This randomized, open-label, 2-way crossover trial was conducted in 36 healthy male volunteers that received OD risperidone tablet, either the reference formulation (Risperdal Quicklet(R) tablet 1mg), or the test formulation (Risperdal OD(R) tablet 1mg), each in a single administration. Blood samples were obtained during a 24-hour period after dosing. Plasma was analyzed for risperidone by a validated LC-MS/MS. Adverse events were monitored by safety assessments including clinical interview by clinician. Pharmacokinetics were calculated by noncompartmental analysis and compared between two formulations. RESULTS: A total of 36 male volunteers (mean age, 24.2 years; height 174.5 cm; weight 67.6 kg) completed the study. The ANOVA showed no significant effect of sequence, formulation and period of Ln (AUClast) and Ln (Cmax). The 90% confidence intervals for the mean treatment ratios of the Ln (AUClast) and Ln (Cmax) were Ln 0.96 ~ Ln 1.12, Ln 0.97 ~ Ln 1.16, respectively. No serious adverse events were caused by both formulations. CONCLUSION: In this study, a single administration of Risperdal OD(R) tablet 1mg was bioequivalent to a single administration of Risperdal Quicklet(R) tablet 1mg.