Over the past few decades there has been outstanding expansion in the surgical exeresis of primary and metastatic liver tumours and particularly hepatic metastases of colorectal carcinomas. With the advance in surgical technique it becomes increasingly necessary to codify the system for the classification and clinical staging of these conditions for the purposes of correct programming of treatment and assessment of the clinical results obtained. The most commonly used systems of classification and clinical staging are analysed, in particular the classifications proposed by the American Joint Committee on Cancer and D. Manfredi for primary liver tumours and those proposed by Gennari et al and Sugerbaker et al for hepatic metastases of colorectal carcinomas. The selection criteria adopted in each system are analysed as the basis for a more thorough discussion of the problem that is felt to be fundamental for the standardisation of classification and clinical staging systems in the future. Such standardisation is essential for the assessment of the value and limitations of liver surgery in cancer