Investigations have been carried out to determine the effect of nitrogen dressings, i.e. basal dressing (N: 5, 10 and 20 g/m²), topdressing at panicle formation stage (N: 4 g/m²) and topdressing at full heading stage (N: 4 g/m²), on the protein, fat, ash, phosphorus, potassium and magnesium contents of lowland brown rice. The results indicated that the ash, phosphorus, potassium and magnesium contents on dry matter basis decreased and the phosphorus, potassium and magnesium contents in ash increased with increasing the amount of basal dressing. With respect to the application of topdressing at panicle formation stage, it was shown that the fat content increased and the ash, phosphorus and magnesium contents decreased on dry matter basis and the phosphorus and potassium contents increased in ash. The application of topdressing at full heading stage gave the increase of the protein content and the decrease of the fat, ash and potassium contents on dry matter basis.