Renal cancers account for approximately 3% of adult cancers and the mean age of diagnosis is 65, with men affected two to three times more frequently than women. However, an increase is being seen in kidney tumours also in young adults and in women. The classification of renal tumours includes both benign and malignant tumours, and is currently quite exhaustive, but may be even more extensive in the coming years, particularly for tumours in renal impairment. Except for certain specific entities (such as chromophobe carcinoma), two criteria are required to correctly classify malignant kidney tumours: the Fuhrman grade, and the pTNM stage, defining tumour extension. The stage and grade are applicable in the same way, regardless of the nature of the tumours; for a given group, they are the best prognostic factors.