Nitrate content of groundwater was surveyed in rural areas of the Beijing Plain from 1999 to 2000.The wells covered in the survey were grouped into four types according to depth and use, i.e.drinking wells (DW) about 120 to 200 m in depth, irrigation wells (IW) about 70 to 100 m in depth, hand-pumping wells (HW) about 6 to 20 m in depth and shallow groundwater (SG) about 3 to 6 m in depth.Findings of the survey show that nitrate content of groundwater is inversely related to depth of the wells.The deeper the well, the lower the nitrate content of the groundwater.NO₃^--N contents of the groundwaters from 145 DWs, 336 IWs, 41 HWs and 77 SGs averaged out at 5.16 mg L^-1, 5.98 mg L^-1, 14.01 mg L^-1 and 47.53 mg L^-1, respectively, and 13.8%, 24.1%, 46.3% and 80.5% of the four types of waters exceeded 10 mg L^-1 NO₃^--N, the international maximum permissible limit for drinking water.Nitrate contamination of groundwater from deep wells was somewhat acceptable, while that of shallow groundwater was terrible.The situation in the suburbs of Beijing, such as Haidian, Fengtai and Chaoyang Districts, was much worse than in the exurbs of Beijing, such as Shunyi, Tongzhou, Changping, Daxing Districts.In the suburbs, 38.7% of the DWs and 52.6% of the IWs had NO₃^--N content above 10 mg L^-1, but in the exburbs, only 3.0% of DWs and 15.3% of IWs did.Nitrate content of Groundwater from wells was remarkably affected by surrounding conditions of the wells.In wells located in vegetable fields, especially old vegetable fields it was more serious than in cereal fields or farmyard.The mean value of 140 IWs located in cereal fields was 2.45 mg L^-1, and only 8.5% of the wells exceeded the limit in NO₃^--N content, while that of 189 IWs in vegetable fields was as high as 8.66 mg L^-1,and 36.0% of the wells did, And also the mean value of 26 SGs located in fields of winter wheat in rotation with summer maize was 18.02 mg L^-1, and 55.4% of the SGs went above the limit, while that of 43 SGs under greenhouses reached as high as 72.42 mg L^-1, and 100% did.Nitrate leaching as a result of overfertilization in vegetable production is the major cause of nitrate contamination of groundwater in rural areas of the Beijing Plain.