The Comet assay has found wide acceptance in monitoring human genotoxicity caused by lifestyle and occupational and environmental factors. In the present study, we have used the Comet assay to measure the DNA damage in a population of rural Indian women cooking with biomass fuels (BMFs; fire wood and cow dung cakes). Out of 144 volunteers, 70 used BMFs for domestic cooking, while the remaining 74 used liquefied petroleum gas (LPG) and served as a reference population. All the individuals had comparable socioeconomic backgrounds and were between 20 and 55 years of age. Significantly higher levels of DNA damage were observed for BMF users than for LPG users. For BMF users in comparison with the reference population, Olive tail moment was 3.83 +/- 0.15 (arbitrary units) vs. 2.77 +/- 0.07 (P < 0.001); % tail DNA was 11.19 +/- 0.35 vs. 8.29 +/- 0.20 (P < 0.001); and comet tail length (microm) was 51.15 +/- 1.37 vs. 40.26 +/- 0.88 (P < 0.001). Similar significant differences were found when the groups were stratified by age and length of exposure. This study suggests that exposure to BMF smoke leads to greater levels of DNA damage than exposure to LPG combustion products.