Abstract: Objective To evaluate the genotoxicity of drinking water in Fuzhou city in vitro.Methods Five districts and a water plant in each district were randomly selected in Fuzhou city.Two hundreds liters drinking water and source water were sampled in a water plant.XAD-2 resin was used to extract the organic matter in the water sample,and single cell gel electrophoresis assay and micronucleus test in vitro were used to detect the genotoxicity of organic extraction.Results The Olive tail-moment for drinking water samples(2,1,0.5 liter) with high contents of organic extraction from water plant B (1.321±0.5,1.310±0.82,1.209±0.48 m),D (1.297±0.48,1.289±0.76,1.235±0.69 m),E (1.553±0.65,1.534±0.68,1.507±0.73 m) and source water samples (2 liters) from water plant D (1.111±0.53 m),E(1 225 0 64 m) were significantly higher than that of negative control(0 530 0 22 m,P < 0. 05 or P < 0 .01).The micronucleus rate for drinking water samples(2,1,0.5 liter) with high contents of organic extraction from water plant B (32.67±11.02,30.00±10.00,26.833±10.17%),D (31.833±5.19,30.17±5.71,26.667±5.50%),E (34.00±7.40,31.00±7.46,27.50± 8.64%),and source water samples (2,1,0.5 liter) from water plant E (30.00±9.88,29.50±9.71,25.50±9.73%),D (27.17±6.59,25.667±7.03%) were significantly higher than that of negative control(14.833±7.70%,P < 0.05 or P < 0.01).Conclusion The drinking water and source water of Fuzhou city were polluted by organic compounds.