This study demonstrates that the deficiency of phytohemagglutinin (PHA) receptors recently shown to be present on the leukemic lymphocyte may be ameliorated by incubating these cells with a biologically analogous material obtained from human saliva. This manuever, performed under controlled, standardized conditions, doubled the capacity of leukemic lymphocytes to incorporate 14C-thymidine during stimulation with phytohemagglutinin in cell culture. The present experiments serve as a prototype for possible in vivo modification of the leukemic lymphocyte surface to make this cell amenable to immunogenic stimuli and potentially more susceptible to chemotherapeutic agents.