This study was conducted to determine some significant characteristics and select superior walnut genotypes within seedling population of Mardin central district and Diyarbakir central districts and their villages during years 2008-2009. Although, Mardin and Diyarbakir central districts have rich walnut genotypes, no studies have been made about walnut trees in the areas up to now. Therefore, this research is very important with respect to be firsting on walnut genotypes in these areas. During this study, firstly about thousand walnut trees were surveyed. Three hundred marked and evaluated in the genotypes. Accoding to results of this research, twelve walnut trees were selected as "promising genotypes'' with respect to fruit quality properies according to the weighted ranked method. In the physical properties of these walnut genotypes, it was determined that fruit weight, fruit length, fruit width, shell thickness, kernel weight and kernel ratio changed from 20.20 to 12.39 g, from 48.86 to 34.11 mm, from 36.71 to 30.45 mm, from 2.26 to 1.40 mm, from 9.55 to 6.73 g and from 58.04 to 40.85%, respectively. Based on the chemical properties of the selected genotypes, it was determined that protein, oil, moisture and ash contents changed from 20.80 to 13.98%, from 68.70 to 57.13%, 4.23 to 1.90% and 2.83 to 1.78%, respectively. In addition, based on the phenological properties of the these genotypes, it was observed that protandrous, protogynous and homogamouus ratios of flowering habits determined to be 50.00%, 33.33% and 16.16%, respectively.