9-hydroxy-2-methyl-ellipticinium (HME) is an intercaling agent mainly potent in metastatic breast cancer. Its almost complete lack of bone marrow toxicity is of greatest value. However, among 385 patients 20 cases of renal failure were observed: renal failure is gradual, non reversible except in four cases with acute renal failure. Histological and ultrastructural studies, performed in 8 cases, showed exclusively proximal tubular lesions, without glomerular or interstitial lesions. We have evidence that there is a relation between the cumulative dose and the severity of the lesions. A prospective study was done in 30 patients. An increase in enzymuria, proteinuria and glycosuria was observed in most patients after HME infusion. HME is an efficient drug in the treatment of bone metastases of breast cancer. Renal function should be carefully monitored during HME administration.