3 weeks after commencing treatment with estramustine phosphate, typical manifestations of hemolytic-uremic syndrome occurred in a 66-year-old patient with prostate cancer. Urinary tract obstructions were excluded and no renal damage could be identified. An improvement in renal function was achieved by stopping estramustine phosphate and infusing adequate amounts of fluids and electrolytes. Anemia and thrombocytopenia also progressively improved after the discontinuation of chemotherapy. Nausea and vomiting, hepatotoxicity, impotence, reduced libido and hypercalcemia are major side effects of estramustine phosphate, and would be difficult to explain our observations without considering the role played by estramustine phosphate. Our observations suggest that estramustine phosphate might play either a direct role or produce a side effect within the context of latent paraneoplastic syndrome. The improvement in renal function which occurred when treatment stopped might confirm our hypothesis.