During a 38-month period the bacteremias developing in patients on hemodialysis from three centers of the Barcelona area were evaluated to assess their incidence, characteristics, and response to therapy. In the overall 13376 months of hemodialysis of the study, 75 episodes of bacteremia were detected in 64 patients; this amounts to an incidence of 5.6 episodes per 1000 hemodialysis months. The most common sources of becteremia were intravenous catheters (44%), which were mainly used as temporary vascular access, followed by the definitive vascular access (26%), the genitourinary system (10%), and the lung (6%). Twenty-seven episodes of bacteremia developed in 24 patients in whom dialysis had been started in the two previous months (11% of the overall number of new patients), and, in them, 77% originated in an intravenous catheter, while this was the origin of bacteremia in only 23% of the remaining patients. 72% of bacteremias were caused by gram positive organisms, particularly Staphylococcus aureus and Staphylococcus epidermidis (60%), followed, in frequency order, by aerobic gram negative bacilli (25%), particularly Escherichia coli and Pseudomonas. Stpahylococci were significantly associated with the vascular access, either if this was a catheter or not (81% of instances), while gram negative bacilli were associated with sources different from the vascular access (48% of instances). Severe complications included 2 cases of aortic valve endocarditis, one hemorrhagic shock caused by rupture of an infected vascular access, and one suppurative phlebitis associated with a hemodialysis catheter. Staphylococcal sepsis was randomly treated with vancomycin or vancomycin plus gentamicin, without differences in the results.(ABSTRACT TRUNCATED AT 250 WORDS)