Two field experiments were carried out during the two successive seasons of 1999/2000 and 2000/2001 to study the effect of some slow release nitrogen fertilizers (Nile compost -enciabein and mixture of them ,Nile compost+enciabein 1:1) with 4 levels (0 ,120,150 and 180  N unit per fed. ) on growth ,yield and its components as well as chemical composition  of potato tubers .The data were  following : 1- Addition of Nile compost as an organic fertilizer resulted the best growth characters. But the mixture of chemical (enciabein) with organic (Nile compost ) had the heaviest tanage /fed. as well as the best physical tuber quality.On the other hand ,the addition of Nile compost as alone and /or mixed with the enciabein gave an enhancement in mineral content, starch, total carbohydrates and total sugars content in potato tuber tissues. 2- The best growth of potato plant was obtained by the addition of the highest levels offertilizer, i.e. 180 N unit /fed. But, the heaviest weight and number of tubers were resulted from the addition of nitrogen within the rates of 150-180 N units / fed. The highest values of starch ,total  carbohydrates , total sugars, N, P, K, and Zn content were obtained by addition nitrogen fertilizer at highest level, i.e. 180 N unit/ fed. concerning the values of Fe and Mn recorded their highest content when potato plants received 150-180 N unit /fed. 3- Application of organic nitrogen fertilizer (Nile compost) at level of 180 N unit /fed. resulted the best growth characters . Used of the mixture of enciabein + Nile compost (1:1) at level of 150 N unit /fed. gave the highest tuber yield as ton /fed., average weight and number and size as well as the highest Fe , Mn, Zn, and Cu . Also, using the mixture of them at highest level 180 N unit /fed. gained the highest values of starch, total carbohydrates, total sugars, N, P, and K content.