HPLC method is developed and validated for determination of three pesticides (abamectin, imidacloprid, and β-cyfluthrin) in water. These pesticides are used widely in agriculture for crops protection, and may be leached to the groundwater. Reversed-phase method with C18 column (5 µm, 250mm × 4.6 mm inner diameter) using a mobile phase consisting of acetonitrile/water (v:v = 4:1) at a flow rate of 1.5 mL/min and UV detection at 220 nm was used. This method is validated according to new methods which include accuracy, precision, linearity and range, limit of detection and limit of quantitation. The current method exhibits good linearity over the range of 1-1000 ppb for abamectin, 0.5-1000 ppb for imidacloprid, and 0.4-1000 ppb for ß-cyfluthrin with r2 greater than 0.990. The percentage recovery of the method at three concentration levels (5, 100, and 1000 ppb) is within 97.6 to 101.5% for the three pesticides. Relative standard deviation of the area of six replicate injections of each pesticide at three concentration levels (5.0, 100.0, and 1000.0 ppb) was found to be less than 1% which reflect the precision of the method. Limit of quantitation of the three pesticides using this method is low (1.0, 0.5, and 0.4 ppb) for abamectin, imidacloprid, and β-cyfluthrin, respectively which enables the determination of these three pesticides in water at low concentration levels.