The purpose of this study is to investigate the bioequivalence of two haloperidol 5 mg tablets, Myung In haloperidol (Myung In Pharm. Co., Ltd., test drug) and Peridol (Whanin Pharm. Co., Ltd., reference drug), and also to estimate the pharmacokinetic parameters of haloperidol in Korean volunteers. The bioavailability and pharmacokinetics of haloperidol tablets were examined on 24 healthy volunteers who received a single oral dose of each preparation in the fasting state in a randomized balanced 2 way crossover design. After an oral dosing, blood samples were collected for a period of 60 h. Plasma concentrations of haloperidol were determined using a liquid chromatographic electrospray mass spectrometric (LC-MS) method. The pharmacokinetic parameters were calculated with noncompartmental pharmacokinetic analysis. The geometric means of AUC0-60h and Cmax between test and reference formulations were 17.21 +/- 8.26 ng x h/mL vs 17.31 +/- 13.24 ng x h/mL and 0.87 +/- 0.74 ng/mL vs 0.85 +/- 0.62 ng/mL, respectively. The 90% confidence intervals of mean difference of logarithmic transformed AUC0-60h and Cmax were log0.9677 - log1.1201 and log0.8208-log1.1981, respectively. It shows that the bioavailability of test drug is equivalent with that of reference drug. The geometric means of other pharmacokinetic parameters (AUCinf, t1/2, Vd/F, and CL/F) between test drug and reference drug were 21.75 +/- 8.50 ng x h/mL vs 21.77 +/- 15.63 ng x h/mL, 29.87 +/- 8.25 h vs 29.60 +/- 7.56 h, 11.51 +/- 5.45 L vs 12.90 +/- 6.12 L and 0.26 +/- 0.09 L/h vs 0.31 +/- 0.17 L/h, respectively. These observations indicate that the two formulation for haloperidol was bioequivalent and, thus, may be clinically interchangeable.