This work was carried out with the aim of evaluating the effect of foliar application of nitrogen in young coffee plants (Coffea arabica L., var. Mundo- Novo). Three sources of nitrogen fertilizers were use: NaN0(3), (NH4)2SO4 and (NH2)2CO 0,7, 0,6 and 0,4 atom % N15 in excess, respectively. Three different methods of application for each source were used: 1) total application of the dosis to the soil; 2) total application of the dosis to the leaves; and 3) fractional application of the dosis, one half to the soil and one half by foliar application. The corresponding checks were also included. The experimental design used was complete randomized blocks, including 14 treatments replicated 3 times. Part of these treatments was in factorial arrangement. The 6 months old coffee plants were grown in a greenhouse during a period of 7 months. The plants were then separated in three fractions: root, stem and leaves. These fractions were oven dried, weighed, ground and total nitrogen and the isotopic relation of 14N/15N were determined. The dry matter yield, the amount of total nitrogen uptake, the quantity of this nutrient coming from the soil and fertilizer, for each treatment and fraction and for the whole plant, were the factors utilized to evaluate the effects of foliar application of the tested nitrogen sources. For the foliar application of nitrogen, a special system of spraying was tried. The most outstanding conclusions obtained are as follows : As a general rule, the effect of the three sources was always similar and the application to the soil followed by the application one half to the soil and one half foliar aplication were responsible for the increased dry matter yield. In relation to the total nitrogen uptake, a higher uptake was obtained with the application to the soil compared to foliar application, for the three nitrogen sources under study. In respect to the nitrogen in these young coffee plants coming from the fertilizes, the application to the soil was also superior to the foliar application. For foliar application, the efficiency of the nitrogen was 12.8%, 9.7% and 8.6% for sodium nitrate, urea and ammonium sulphate, respectively. In one half soil and one half forliar application, the efficiency was 33.5%, 23.3% and 22.7% for sodium nitrate, ammonium sulphate and urea, respectivaly. Nitrogen translocation from the top to the roots of the plant was evident when applied through the leaves. In the half to the soil half to the leaves treatment with ammonium sulphate, no similar results were obtained. It is difficult to explain the low absorption of nitrogen applied to the leaves for the three sources, sodium nitrate being superior to urea.