In the present publication we discuss nephrotoxicity (NT) incidence by reviewing all the clinical histories of one year (May 1989-May 1990) with diagnosis of obstructive jaundice or cholangitis. Of a total of 90 patients. 53 were treated with aminoglycosides and 37 received other antibiotics. Nephrotoxicity developed in nine patients of the group that received aminoglycosides (17%), versus only three patients (8%) in the other group. Both groups were comparable regarding sex, age and liver and renal basal functions. Analysis of the variables that could be associated with a higher incidence in the nephrotoxicity group that received aminoglycosides showed that there were no differences regarding age, sex, dosage, duration of treatment, plasmatic levels of aminoglycosides and liver and renal basal functions. Only simultaneous administration o furosemide was significantly associated with the development of nephrotoxicity. Results of this study underline the need of a prospective follow-up of patients with biliary obstruction during treatment with aminoglycosides. Meanwhile the evidence available allows us to recommend the monitoring of renal function in this type of patients.