Increased incidence of cancer at various sites is observed in patients with end-stage renal disease (ESRD). In particular, lymphomas and carcinomas of the kidney, prostate, liver and uterus show an enhanced prevalence in these subjects compared with the general population. A multitude of factors directly or indirectly associated with the renal disease and the treatment regimens may contribute to the increased tumor formation in these patients. Impaired function of the immune system and of DNA repair mechanisms as well as reduced antioxidant defense, accumulation of carcinogenic compounds partly due to reduced renal elimination as well as chronic infections and inflammations are found more frequently in patients with ESRD compared with the general population and may act in concert to accelerate malignant transformation and tumor formation.