Recent studies of the malignant phenotype have suggested that cumulative genetic changes are necessary for a malignant cell to develop. Alterations in particular genes associated with cell growth and division have been identified and two main classes of genes have been characterized. Oncogenes are those genes which when mutated promote tumour growth, whereas tumour suppressor genes (antioncogenes) inhibit tumour growth. Oncogenes have been investigated in some depth, but relatively little is known about tumour suppressor genes. Recent studies have shown that inactivation of normal tumour suppressor genes is a common mechanism in cancer progression and this may be of prognostic value. The present review focuses on the potential of tumour suppressor genes as prognostic markers in urological cancers.