Winter and spring frost damage to fruit and nut trees is common so growers are interested in insuring their crop against losses. The purpose of this work was to develop a model that could be used for this purpose in walnut (Juglans regia L.) orchards. During 2010, 40 seedling walnut trees from Koleeim and 39 from Jezla, the two main walnut growing locations of Tarom, in Zanjan province in Iran, ranging in age between 10 and 50 years old, were selected at random. Trunk circumference (TC), trunk cross sectional area (TCA), canopy radius (CR), lateral bud fruiting (LBF), tree growth habit, average annual shoot growth (SHGPY), the ratio of external/internal fruit bearing shoots in the canopy, dichogamy, fruit set in the spring, fruit weight, kernel percentage, and number of fruits per tree, were recorded. Yield per tree was calculated using nut weight and number of nuts per tree. The effect of these traits as independent variables on nut yield as a dependent variable was studied using multiple linear regression models. The data from two sites were used separately and as a pooled set for analysis. Results were validated using a second set of data. The best-fit model employed trunk circumference and lateral bearing percentage as independent variables: Y= (0.12465 * TC) + (1.32889 * LTB),Y= (0.15071 * TC) + (0.55075 * LTB) and Y= (0.14049 * TC) + (0.93873 * LTB).Coefficients of determination were 0.8417, 0.8773, and 0.8526 for the two sites and the pooled data respectively.
