Correlation and causal relationships among 21 horticultural traits were determined using 71 walnut genotypes selected from seven valleys in Kerman Province, Iran. Pearson's correlation coefficient was calculated. Kernel percentage and blight susceptibility were used as dependent variables in a stepwise regression model to determine predictor variables. Direct and indirect effects of each independent variable were calculated using path analysis. A highly significant correlation was observed between lateral bearing habit and yield. Lateral-bearing trees were also more susceptible to blight and winter cold than terminal bearers. Kernel and nut weights, shell thickness, and difficulty of extracting kernel halves were the most important traits accounting for kernel variation. Kernel weight and difficulty extracting kernel halves had the strongest positive direct effects and nut weight the most negative. Flowering habit, nut shape, and leafing date had positive direct effects on blight susceptibility, but the large residual effects suggest there are other important determinant traits for blight susceptibility, which were not considered in this study.