Our service performed a total of 619 kidney transplants between February 1980 and March 1993. Among them, 41 new neoplasias (6.6%) were diagnosed. Most frequent tumour was epithelioma (25) with a presentation age lower than in the normal population. Amongst the remaining tumours (16), the occurrence of 2 lymphoma and 2 Kaposi's sarcoma should be emphasized, together with the fast evolution progression of the others. Using a multiple regression model, an analysis is made on the influence certain factors have in the development of neoplasias, age being selected as the only significant one. The relative risk transplanted subjects have of suffering some type of neoplasia compared with the normal population is 36.