The present paper reviews some results of the studies on utilization of nitrogen specifically by vegetable crops, which were conducted in Japan in the 1980s. Those studies employed mainly a ¹⁵N tracer method. The topics included in this review are: absorption, reduction and/or assimilation, translocation and partitioning of nitrogen, ammonium toxicity and its alleviation by nitrate. Application of nitrogenous fertilizers and its utilization by plants are also discussed. Based on the results of those studies, it is concluded that the ¹⁵N tracer method is easy and harmless in dealing with and useful in pursuing dynamic movements of nitrogen in soils and plants as well as those from soils to plants.