Varieties of wheat and lowland rice were grown in complete nutrient solutions supplied with different chemical forms of nitrogen. Sodium nitrate, ammonium sulfate, and urea and combinations of sodium nitrate and ammonium sulfate to furnish nitric and ammoniacal nitrogen in the ratios of 1 to 3, 2 to 2, and 3 to 1 were used to supply chemically equivalent amounts of nitrogen. The plants were harvested in three growth stages and dry weight of plants and certain nitrogen fractions in the plants were determined. Both species of cereals assimilated all forms of nitrogen to a certain extent. On the whole, rice was more at home with ammonium sulfate than was wheat. Both kinds of plants assimilated nitrogen from ammonium sulfate better in the early stages than in the later stages of growth. The best growth of rice in all stages of growth was obtained with the 3 to 1 ratio of nitric and ammoniacal nitrogen and of wheat with the same ratio except that in the second stage urea gave the greatest weight. Toxicity of ammonium sulfate was more pronounced with wheat than with rice, and this toxicity increased with the age of the plant. The toxic effect rather closely paralleled the amount of ammoniacal nitrogen found in the plants. Rice exhibited a much higher iron requirement than did wheat.