A fast and sensitive reverse phase HPLC-UV method for the separation and quantitation of haloperidol and its related compound 4,4′-Bis[4-(p-chlorophenyl)-4-hydroxypiperidino] bu-tyrophenone} in both drug substance and tablet dosage form is reported. A non-porous silica (NPS) ODS-1 column was used as the stationary phase and the mobile phase consisted of 77:23 v/v 50 mM phosphate buffer with 0.2% triethylamine (TEA) pH 2.5/acetonitrile. The flow rate was 1.0 mL/min with detection at 220 nm.