Abstract: HPLC was applied to the determination of the insecticides carbofuran and carbaryl in water with post-derivatization. The water sample was adjusted to pH 3 with HCl and filtered with hydrophilic filtering membrane of 0.45 μm. 200 μL of the filtrate was taken for HPLC analysis. Waters Carbamate Analysis column (3.9 mm×150 mm, 5 μm) and mobile phase of a mixture of methanol-acetonitrile-H2O (1+1+3) were used in the separation. The eluate was hydrolyzed with 2 g·L-1 NaOH solution and derivatized with a solution containing 0.1 g phthaldehyde, 19.1 g of sodium borate (10 hydrate) and 0.5 mL of 2 mercaptoethanol per liter of the solution. Fluorescence detection was made at λex 339 nm and λem 445 nm. Detection limits (3S/N) found were same as 4×10-4mg·L-1 for both the insecticides. Samples of tap water and river water were analyzed by the proposed method and recovery was tested by addition of standards, values of recovery found were in the ranges of 93.0%-98.0% (for carbofuran) and 93.0%-99.4% (for carbaryl) with values of RSD′s (n=6) less than 0.50%.