Background: Infection is a frequent complication in patients with end-stage renal disease. The most common organisms isolated are gram-positive cocci and gram-negative bacilli. Therefore, the usual initial therapeutic approach in these situations is the simultaneous intravenous administration of vancomycin plus an aminoglycoside. This treatment's adverse effects include ototoxicity, nephrotoxicity, and less than ideal tissue penetrance. Methods: We assessed the efficacy of intravenous ceftriaxone in the prevention and in the initial empirical treatment of infections in end-stage renal disease patients, and tested the stability of blood levels of this antibiotic in this population. We studied 104 patients, 65 of them falling into the prevention group (1 g of ceftriaxone i.v. for 5 days) and 39 into the treatment group (1 g of ceftriaxone i.v. or intraperitoneally for 10-14 days). Results: Peak serum ceftriaxone concentrations were well above the minimal inhibitory concentration for 90% of strains. Trough serum concentrations of the drug prior to the next dose were also considerably in excess of the minimal inhibitory concentration. In the prevention group, 8 of 65 developed an infection, which was sensitive to ceftriaxone, whereas in 22 of the 39 patients from the treatment group, cultures showed organisms sensitive to ceftriaxone and in the remaining 17 patients sensitivity was not done. Conclusions: The present study demonstrates the efficacy of a simplified dosing schedule in achieving blood levels of the antibiotic well in excess of minimal inhibitory concentration of any of the organisms encountered. It also shows the usefulness of ceftriaxone in the prevention and/or treatment of bacterial infections and the lack of the side effects vancomycin and/or aminoglycosides possess.