Optimum conditions for extraction of quercetin and kaempferol from coriander are determined using experimental design and HPLC method. Effects of five experimental factors, including percentage of methanol in aqueous extraction solvent, volume of extraction solvent, concentration of HCl used for hydrolysis, extraction time, and temperature on the extraction recovery, are investigated.Central composite design is used to investigate the effects of these factors and grid search method is used to find the optimum conditions. The optimum conditions are 30 mL of 45% aqueous methanol, containing 1.85 M HCl, refluxed for 2 hours at 84°C. The extraction procedures at optimum conditions for quercetin and kaempferol show good repeatability with relative standard deviations of 3.6%, 4.0% and recoveries of about 96%, 94%, respectively. Limit of detection (LOD), Linear dynamic range, intra-day and inter-day R.S.D for quercetin and kaempferol are 0.19, 0.18, 0.19-48.0, 0.18-30.0 μg/mL (R2 = 0.99), and 3.0% - 4.0% respectively.Concentrations of quercetin and kaempferol in Coriander are found to be 23.1 and 10.1 mg/Kg respectively.