Abstract: The FIA apparatus used was as described previously (cf., Anal. Chim. Acta, 1992, 269, 193), the various parts of the apparatus being connected with PTFE tubing (0.5 mm i.d.). The pesticides studied were bendiocarb, chlorophacinon, coumatetralyl and pirimiphos-methyl (which fluoresce naturally) and fenitrothion, fenvalerate, deltamethrin and diflubenzuron (which fluoresce under 254 nm radiation). For the photo-induced fluorescence, the mobile phase/sample mixture passed through a reaction coil (2.5 m), loosely wrapped round an 8 W germicidal lamp and covered with Al foil. The parameters optimized were the type of mobile phase, flow rate, sample volume, reactor and mixing tube lengths and excitation and emission wavelengths (tabulated). Calibration graphs were linear over two orders of magnitude, ranging from 0.1-20 ng/ml for coumatetralyl to 0.11-15.7 µg/ml for bendiocarb (both with 0.3 mL injected), with detection limits of 0.02-22 ng. Methods are given for extracting the pesticides from technical formulations, with recoveries of 91.9%. In a mixture of fenitrothion and fenvalerate (sumicombi) there was interference from fenvalerate, but the mixture could be analyzed by selective suppression of fenitrothion fluorescence (in methanol solution) and of fenvalerate fluorescence (in DMSO). The method was applied to the determination of five pesticides in tap water.