Background: Staphylococcus aureus bacteremia (SAB) may be complicated by endocarditis or metastatic infection without evidence of endocarditis (MIWE). The aim of this study was to identify risk factors for MIWE and endocarditis in patients with SAB. METHODS: We performed a retrospective chart review to compare characteristics of patients with uncomplicated SAB and patients whose SAB course was complicated by MIWE or endocarditis. We reviewed the charts of patients with SAB diagnosed in our department from 1992 to 1999 for S. aureus portal of entry, secondary foci of infection, underlying conditions, previous valvular defects, and foreign material. Endocarditis was defined according to the Duke criteria. Patients were classified as having MIWE when the diagnosis of endocarditis was not definite according to the Duke criteria and when there was evidence of at least one secondary metastatic infection other than endocarditis. RESULTS: Some 109 patients had 111 episodes of SAB. Sixty-three patients had no evidence of metastatic infection and constituted the control group. Twenty-seven patients developed at least one episode of MIWE. A community-acquired SAB (CI 95% OR: 1.4-12.3, P<0.02), two or fewer underlying conditions (CI 95% OR: 1.2-83, P<0.04), and a non-severe portal of entry (CI 95% OR: 1.2-20, P<0.03) were independently predictive for MIWE. The characteristics of 21 patients with endocarditis were compared with those of the control group. Only a previous valvular defect was significantly associated with endocarditis. CONCLUSION: A previous valvular defect seems to be an important factor for developing endocarditis during SAB. Risk factors for having MIWE may differ from those found for patients with endocarditis.