A sensitive and selective spectrophotometric method has been developed for the determination of six phenothiazine neuroleptics. The method is based on the interaction of the drugs with chloramine-T in sulphuric acid medium to yield a red, reddish-violet, orange or greenish-blue intermediate with maximum absorption at 500-636 nm. Beer's law is obeyed over the range 5-125 μg ml−1of the drugs. The apparent molar absorptivities were found to be in the range 1.04x103to 5.46x1031.mol−1cm−1. The investigated drugs were assayed in tablets and injections. The mean percentage recoveries were 97.65-101.75 and the relative standard deviations were found to be less than 2%.