Abstract: Linkage relations among eight isozyme genes, Acp3, Est1, Est5, Prx1, Prx2, Prx3, Me and Adh, and two morphological markers, Inh and Twh, were investigated in one F₂ and two BC₁ families of interspecific crosses between the American chestnut (Castanea dentata Borkh)and the Chinese chestnut (C.mollissima Blume), Inh was found to be consistently linked with Prx1 and Est5 in all families. The order of these three genes was determined to be Inh-Prx1-Est5.In addition, four other gene pairs, Acp3-Inh, Acp3-Prx1, Me-Inh and Twh-Inh were found to be linked in one of the three families Investigated.The two isozyme genes and two morphological marker genes were tentatively integrated into one linkage group with the following gene order Twh-Inh-Prx1-Est5.This study demonstrated that isozyme genes can be integrated with morphological marker genes into a single linkage map without the need for additional crosses.the inconsistencies observed in detecting linkage relationships among the chestnut families were discussed.