The prevalence of cancer in renal transplant patients is greater than in the general population. It is influenced by demographic and ethnic characteristics. We performed a retrospective study of 793 patients who received 872 kidney transplants at our center during 23 years. The age at transplantation was 41.4+/-14.0 years, the follow up 75.4+/-69.4 months. The cohorts include 203 patients treated with azathioprine-prednisone; 510, cyclosporine-based therapy; and 159, tacrolimus-based therapy. There were 95 patients (10.9%) who developed at least one neoplasm with 9 having more than one type of tumor. The incidence was of 17.3 cases per 1000 patients-years. Forty-four (46.3%) had skin cancer, 8 (8.4%) Kaposi sarcoma and 43 (45.3%) a non-skin cancer. Seven of eight patients with Kaposi sarcoma were on CsA therapy. The risk of developing a neoplasm at 5, 10, and 15 years was 8%, 17%, and 30% respectively. In a multivariate analysis, the risk factors associated with neoplastic diseases were older age (OR=1.061; 95% CI 1.039-1.084; P=.000), male sex (OR=2.658; 95% CI 1.536-4.599; P=.000), length of follow-up (OR=1.121; 95% CI 1.073-1.172; P =.000), and immunosuppression with CsA (OR=4.448; 95% CI 1.334-14.764; P=.015). Cancer was the cause of death in 26 patients, the fourth most common cause after cardiovascular disease, infection, and liver failure. We conclude that malignancies are an important cause of morbidity and mortality among transplant patients. Special attention must be devoted to older male patients with a long-term follow up to develop preventive and surveillance strategies.