Walnut (Juglans regia L) has various microelement and nutritious substances and is one of the important nut crops. In the present research, 89 walnut genotypes were selected from different regions of Iran and evaluated to determine phenotypic diversity and to detect superior trees. The variability was detected for nut and kernel characters. Nut and kernel characters were predominant into the first three principal components and explained most of the total variation. The most of simple correlations were to be found between the variables of nut and kernel sizes. Principal component and cluster analyses indicated a high variation among the studied genotypes. The results indicated that most of genotypes were suitable in terms of consistent kernel percentage and color and can be singled out for cultivation. Furthermore, they could be useful as a parent to be crossed to generating appropriate populations or improve cultivars. In conclusion, two key variables, kernel weight and nut weight, were the important traits accounting for kernel percentage which should be regarded in breeding programs.
