A high performance liquid chromatographic (HPLC) method for the determination of formaldehyde, acetaldehyde and propionaldehyde in packed drinking water was developed. Aldehydes were derivatized with 0.5 mL DNPH (2,4-dinitrophenylhydrazine) reagent and 0.1 mL 2 M perchloride at 55°C in 60 minutes, then adsorbed in C18 glass cartridge (was performed), eluted with 5 mL acetonitrile ,and finally determined by HPLC. Formaldehyde, acetaldehyde and propionaldehyde-DNPH-derivatives were seperated on a Cosmosil 5C18-MS column by using acetonitrile/D.I. water (55/45, v/v) as a mobile phase, and detected with UV 360 nm. Recovery studies were performed by fortifying D.I. water with formaldehyde, acetaldehyde and propionaldehyde at various concentrations from 2 to 200 ppb. Recovery rates were in the range of 84.4 – 103.2%, 90.2 – 122.1% and 60.8 – 100.4%. The detection limits for all three aldehydes were 1 ppb. Sixty-three packed drinking water samples collected from various markets were analyzed. These results were well below the guideline for drinking water quality by WHO (900 μg/L).