A low CD4 lymphocyte count has been associated with skin and nonskin cancers in kidney transplant recipients (KTR) and might be a useful prediction tool. We analyzed the serial measurements of CD4 and CD8 lymphocytes to study the influence of immunosuppressants and look for a possible predictive value of lymphocyte count for the occurrence of cancer. In 250 successive KTR, blood lymphocytes were labeled for CD4 and CD8 count, prior transplantation, at month 3 and 6 and each year thereafter, throughout a 10-year observation period. The kinetics of lymphocyte subsets were compared in regard to treatments, cancer and confounding factors. ATG were responsible of an early and long lasting impairment in CD4 cells. Patients with a cancer and especially those with multiple tumors, presented with less CD4 cells throughout the observation period, but ATG were not directly associated to the occurrence of tumors. An early low CD4 count was of poor predictive value for the occurrence of cancer.