In summary, some evidence indicating an increase in incidence of renal parenchymal malignancy has been presented. The nature of renal adenoma and its relationship to renal carcinoma remain uncertain, but it is possible that improved computerized tomography will allow in vivo identification of these lesions and initiate a long-term study to provide some clear data on their natural history. The heterogeneity of clinical presentation of this disease has been reviewed and the paraneoplastic syndromes and their importance summarized. Careful clinical and postmortem studies of disease spread, especially lymphatic spread, have been shown to provide useful information to the debate on the role of lymphadenectomy. Many of the unusual aspects of the natural history have been interpreted in terms of the hosts immune response and some data on the complexity and specificity of the host tumor interaction presented. In conclusion, an understanding of the natural history of renal carcinoma forms an important background on which to base clinical management and identifies areas worthy of further investigation in this curious tumor.