We examined the effects of soluble sugar, juglone and total flavan concentration of scionwood on graft success in walnut (J. regia L). According to simple regression analysis, graft success was linearly related to sugar and juglone concentrations, and quadratically related to flavan concentration. In addition, the best multiple regression model was constructed for graft success according to Al possible regression approach. It was found that the best model included linear terms for flavan and sugar, quadratic term for flavan and the interaction term for flavan x sugar. The r square (R-2) for this model was 0.72, meaning that this model, explained 72% of variation in graft success. The residual variation (28%) resulted from other factors.