With improved methods for preventing extramedullary relapse in the leptomeninges and gonads, the problem of clinically isolated relapse at other sites has become more significant. The authors report here two children with acute leukemia who developed mandibular relapse while in complete hematologic remission. One had been off chemotherapy for acute lymphoid leukemia for 2.5 years. The other child is apparently the first patient with promyeloid morphologic features to experience relapse at this site. Both children are in second complete remission and off treatment after local radiation therapy and second courses of chemotherapy. Review of these two and five previously reported isolated mandibular relapses in childhood leukemia indicate that they are usually delayed until after cessation of therapy. Treatment with radiation and combination chemotherapy can result in long remission and possibly cure.