This study was carried out at the greenhouse of Ornamental Hort. Depart, Fac. of Agric.,Cairo Univ.,during two seasons : 2002 and 2003 to investigate the response of Dieffenbachia maculata cv."Exotica" to some nitrogen sources.On 3rd March, 2002 and 2003, uniform terminal rooted cuttings (4 leaves and 20 cm height) were planted in 18 cm plastic pots filled with a mixture of peat moss + sand + perlite (4 : 2 : 1 v / v / v).The fertilizer treatments of N-sources were applied, as a soil drench at the rate of 1gm N./pot,at 2-week intervals, starting from 15 th April and were continued till 15 th November. The results revealed that the tallest plants were obtained when amm. nitrate, amm. sulphate and their mixture were used as N-sources. These N-sources also increased the formation and dry weight of leaves and length as well as fresh weight of the roots. amm. nitrate gave the thickest and the heaviest stems. The combined treatment of amm. sulphate + amm. nitrate was the most effective in increasing the area and fresh weight of leaves. The application of amm. sulphate or amm. nitrate markedly increased the percentages of chlorophyll-a and b, whereas, the percentage of total carbohydrates in the leaves was greatly increased to amm. sulphate, calcium nitrate or urea. All N-sources increased the N- percentage of leaves and amm. sulphate was the most effective. Fertilizing the plants with calcium nitrate increased the accumulation of P in leaves. The treatments of amm. nitrate, urea and the mixture of amm. nitrate + amm. sulphate gave the highest accumulation of K in leaves.