A simple and rapid spectrophotometric method for the determination of seven phenothiazine derivatives has been performed either in pure form or in their dosage forms. The method is based upon the interaction of the drug in dry chloroform with bromophenol blue in the same solvent to produce a stable yellow ion-pair complex which absorbs at 410 nm, with high apparent molar absorptivity. Beer's Law is obeyed in the concentration range 1−10 ugml−1for the studied compounds. The mean recoveries range from 99.80±0.74 to 100.50±1.33. The proposed method is applied for the analysis of the studied compounds in their commercial preparations. Results are in good agreement with those obtained by official methods.