A new, simple and sensitive pre-column fluorescence derivatization high-performance liquid chromatographic method for the determination of the oxidative DNA stress marker, 8-oxo-7,8-dihydro-2′-deoxyguanosine, was developed. Solidphase extraction using an Oasis HLB cartridge avoided troublesome sample preparation steps, interference from charged species and frequent and essential electrode maintenance in electrochemical procedures. 8-Oxo-7,8-dihydro-2′-deoxyguanosine and other guanine compounds were selectively derivatized with glyoxal reagents (phenylglyoxal, 3,4-methylenedioxyglyoxal, 2-naphtylglyoxal and 6-methoxynaphthylglyoxal) at 40-60°C. Derivatization with 6-methoxynaphthylglyoxal at 40°C for 30 min gave the strongest fluorescence product. The fluorescence derivatives from reaction with 6-methoxynaphthylglyoxal were separated on a Capcell Pak C 18 SG 120A column (4.6 mm i.d. × 150 mm, 5 µm) with acetonitrile-5 mM phosphate buffer (pH 6.0; 3:7, v/v) as mobile phase. The detection wavelength of the fluorescence derivative of 8-oxo-7,8-dihydro-2′-deoxyguanosine was λ ex 400 nm and λ em 510 nm. The detection limit of 8-oxo-7,8-dihydro-2′-deoxyguanosine was 1 ng/mL using 50 mL of urine. The calibration graphs were linear up to 30 µg/mL for 8-oxo-7,8-dihydro-2′-deoxyguanosine. The relative standard deviation of 20 ng/mL of 8-oxo-7,8-dihydro-2′deoxyguanosine was 7.0%. The proposed method was compared with the enzymatic ELISA 8-oxo-7,8-dihydro-2′-deoxyguanosine analysis method (8-OH-dG Check, JaICA, Shizuoka, Japan). The correlation coefficient was 0.79 (n = 20) and y = 0.85x + 5.34. The proposed method was applied to the monitoring of 8-oxo-7,8-dihydro-2′-deoxyguanosine in urine from male heavy smokers.