This is the first paper to describe the use of a one-way mixed lymphocyte reaction (MLR) for the immunological evaluation of various types of allogeneic cortical bone grafts, i. e., fresh, frozen, and freeze-dried, to the mandibles of dogs. A total of 35 mongrel dogs (26 males/9 females) were used for this one-way MLR evaluation. The experimental design included the evaluation of three types of allogeneic cortical bone-grafts: fresh bones (Group 1), frozen bones (Group 2), and freeze-dried bones (Group 3).Of the 35 dogs, 10 (6 males/4 females) were used as bone donors and 25 (20 males/5 females) as bone graft recipients. The one-way MLR was used to evaluate immunological differences between the donors and the recipients and the degree of transplant rejection.The MLR results are summalized below:1) Of the 3 groups, the fresh cortical bone grafts showed the highest stimulation index (S. I.) value;2) Of the 3 cultures examined, the freeze-dried cortical bone graft cultures showed the highest S. I. value for the longest period, whereas in the fresh bone graft cultures the S. I. value was maintained for the shortest period.Based on these findings, it was concluded that freeze-dried cortical allogeneic bone grafts elicit the lowest cell-mediated immunity.