A new post-chemiluminescence (PCL) phenomenon was observed when phenothiazine medications were injected into the reaction mixture after the chemiluminescence (CL) reaction of luminol and potassium ferricyanide had finished. A possible reaction mechanism was proposed based on studies of the kinetic characteristics of the CL, CL spectra, fluorescence spectra, and on other experiments. The feasibility of determining various phenothiazine medications by utilizing these PCL reactions was examined. A molecular imprinting-post-chemiluminescence (MI-PCL) method was established for the determination of chlorpromazine hydrochloride using a chlorpromazine hydrochloride-imprinted polymer (MIP) as the recognition material. The method displayed high selectivity and high sensitivity. The linear range of the method was 1.0 x 10(-8) approximately 1.0 x 10(-6), with a linear correlation coefficient of 0.9985. The detection limit was 3 x 10(-9) g/ml chlorpromazine hydrochloride, and the relative standard deviation for a 1.0 x 10(-7) g/ml chlorpromazine hydrochloride solution was 4.0% (n = 11). The method has been applied to the determination of chlorpromazine hydrochloride in urine and animal drinking water with satisfactory results.