This work was carried out during the two sum-mer seasons of 2006 and 2007 at Arab El-Awammer Research Station (A.R.C.); Assiut, Egypt, to study the effect of Enciabien as a slow- release fertilizer on sweet potato plants grown in newly reclaimed soil. Three genotypes of sweet potato ( two clones Assiut 201, 202 and one culti-var 17/8) and four levels of nitrogen i;e. 20 N units of ammonium sulphate (control ), 20 N units , 40 N units and 60 N units of Enciabien were used in the present study. The results indicated that applying 60 N units of Enciabien gave the best result in most of studied characters. Also, genotype Assiut 201 was the best genotype under the experiment condition for the most studied characters. The in-teraction between 60 N unit of Enciabien and culti-var 17/8 gave the highest averages of vine weight, main stem length and highest number of branch-es/plant, while the interaction between 40 N units of Enciabien and Assiut 201 gave the best number of marketable storage roots/plant, weight of mar-ketable storage roots/plant, total yield/fed and av-erage of root diameter. High dry matter content and high starch root percentage were obtained from genotype Assiut 201 when received any of four tested nitrogen levels. While, high percentage of fiber in sweet potato roots were obtained from the interaction between Assiut 202 and all levels of nitrogen. The highest percentage of sugar content in sweet potato roots was obtained from cultivar 17/8 when received any of four used N levels.