Abstract Since the 1980s, nitrogen fertiliser consumption in China has increased substantially. High nitrogen application rates may increase the potential groundwater N-pollution. These effects were investigated in 14 cities and counties in northern China. The Merckoquant-nitrate-test strip was used to measure the nitrate concentration in water. Information on well depth, groundwater level, crop rotation, yield and fertiliser application was obtained. The results demonstrated that nitrate pollution of ground and drinking water has become a serious problem. At over half of the 69 locations investigated, which were distributed over an area of about 140 000 km 2, nitrate content in ground and drinking water exceeds 50 mg l −1, the allowable limit for drinking water. Critical situations were found in vegetable-producing areas, drinking water in the centres of small cities and towns and in farmers' yards, where nitrate contents in ground and drinking water were measured at 300 mg NO 3 l −1. In all locations with high nitrate content in the water, N-fertiliser was applied in large quantities, ranging from 500 to 1900 kg N ha −1 and the percentage of applied N taken up by crops was below 40%. An increase in the food requirements of an increasing population and the decrease in land resources in China will cause agriculture to intensify in the future. Fertiliser applications are expected to double or even triple within the next 30 years, making the problem of nitrogen fertiliser related pollution even more serious. Based on investigations and analysis, some suggestions for solving the problem, such as best management practices for nitrogen fertiliser and improving environmental awareness, are discussed.