Experiments were carried out to make clear the relationships among some morphological characters of four-varieties of mulberry trees. Simple correlation coefficients and particial correlation coefficients were calcultated among the characters, namely branch length, branch diameter, leaf number per branch, leaf area per branch, node number per branch, total branch wt. branch weight except leaves and leaf weight per branch of the mulberry trees. The results obtained are summarized as follows: 1. Variances of the characters and covariances between the each characters are shown in table 1, and simple correlation coefficients among various characters are shown in table 2. It was observed that there were close relationships between yield (leaf weight) and branch length, branch diameter, leaf number per branch, leaf are per branch, node number per branch, total branch weight and branch weight except leaves, respectively. 2. Partial correlation coefficients among some characters are shown in table 3. From this table, it was also observed that leaf yield of mulberry trees and leaf area are more closely related more than leaf yield and the other characters of mulberry trees in four different varieties. From the experimental studies, it was recognized that the four characters, namely branch length, branch diameter, leaf number and leaf area, should be very useful characters in the estimation of mulberry leaf yield as they could be measured. or counted easily before harvest of mulberry leaves, and are affected more in mulberry 1eaf yields than the other characters.