The incidence of the tumor markers was studied in 140 patients aged between 18 and 84 years who had been on dialysis for 4–188 months. Neuron-specific enolase increased in 81 cases, CA-50 carbohydrate antigen in 44, while α-fetoprotein was within the normal range. Carcinoembryonic antigen (CEA) with 2 monoclonal assays was increased in 7 cases. When polyclonal assays were used, CEA was found to be elevated in 12 cases with one set and in 72 cases with another kit set. The data point (1) to the potential usefulness of these markers for the detection of malignancy and possibly neuropathy in uremia; (2) to the importance of renal tubules in the metabolism of proteins, glycoprotein and peptides, and (3) to the activation/inhibition in various enzyme systems in the uremic state.