A specific, high performance liquid chromatographic method was developed for the assay of haloperidol, together with an adequate separation of its degradation products. The method is based on the use of an octadecylsilane stationary phase column under isocratic conditions. The mobile phase consisted of 50 mM sodium phosphate monobasic pH 2.5-acetonitrile-THF-TEA (63:34:3:0.1, v/v/v/v) adjusted with o-phosphoric acid to a pH of 2.5. The degradation was performed in hydrochloric acid, sodium hydroxide and hydrogen peroxide. The main degradation products were identified. Application of the assay of haloperidol in tablet formulations is presented.