In this retrospective historical study, we compared the incidences of malignancies observed among 854 renal transplant recipients (RT) with at least 1 yr of follow-up, with the incidences of neoplasias among patients under regular dialytic treatment (RDT) and a control population from Northern Italy. Cox's proportional hazard model was used in RT recipients in order to evaluate the prognostic factors related to the development of neoplasia. Seventy six out of 854 RT patients (8.9%) developed some malignant neoplasia: 46% of these 76 were cutaneous neoplasias including melanomas, and the remaining 54% non cutaneous cancers: 33% miscellaneous tumors (MT), mostly adenocarcinomas, 17% Kaposi's sarcomas (KS), 4% non-Hodgkin's lymphomas (NHL). Malignancies had a higher incidence (p < 0.01) among RT recipients than among control and RDT patients. However, MT were equally frequent among the three groups. RDT patients on the contrary, had similar incidence of neoplasias when compared to the control population, but showed a lower incidence of squamous cell carcinomas (SCC). The risk ratios (RR) for the most frequent neoplasias among RT recipients vs. control population were: 224.7 for KS, 7.4 for NHL, 6.2 for SCC, 5.7 for basal cell carcinomas (BCC), 4.0 for MT. The risk of developing a de novo neoplasia was of about 13% at 10 yr and of 34% at 20 yr. In RT recipients, Cox's proportional analysis showed that age > 40 at transplantation and male sex were the only risk factors associated with an increased incidence of neoplasias, while no difference was observed between conventional (azathioprine+methylprednisolone: Aza+MP) and CsA therapy or in CsA monotherapy vs. double or triple therapy. However, KS occurrence correlated both with CsA dose (RR 15.2 for monotherapy; 12.5 for double therapy; 2.98 for triple therapy) and with 10 or more i.v. methylprednisolone pulses for treatment of rejection (RR 5.2). We conclude that in our series CsA does not increase the risk for development of neoplasias, when compared to conventional immunosuppression.