Fluorimetry and photochemically induced fluorimetry (PIF) are proposed for the quantitative analysis of four psychotropic drugs, including ethopropazine (EPZ), levomepromazine (LPZ), thioproperazine (TPZ) and trifluoperazine (TFZ). The influence of ultraviolet (UV) irradiation time on the fluorescence excitation and emission wavelengths and intensity was investigated in aqueous buffer solutions (pH 4 – 6) at room temperature (298 K). The selected UV irradiation times were between 10 and 50 s, depending on the compound. Linear calibration graphs were established over about two to four orders of magnitude, with relative standard deviations in the range 2.0 – 5.4%. PIF limits of detection were comprised between 2.6 and 8 ng ml−1, depending on the compound. The PIF method was found to be more sensitive and more reliable than conventional fluorimetry for the phenothiazine derivatives under study. PIF was applied to the determination of these compounds in urine and pharmaceutical samples. The mean recoveries ranged from 88 to 119%.