Introduction: P. aeruginosa causes serious infections with high mortality., Objectives: Identify the prognostic factors associated with higher mortality in P. aeruginosa bacteremias (PAB)., Methods: 211 consecutive cases of PAB were analyzed prospectively between 1992-1998. Blood cultures, isolation, and antimicrobial sensitivity were carried out according to microbiology standard methodology. The variables analyzed as prognostic factors were: sex, age, source of infection, background, main disease, initial clinical severity, foci, presence of complications, leukocyte count, type of antibiotic treatment and adaptation. Bivariate and multivariate statistical analyses were carried out by the method of logistic regression., Results: Global mortality was 27.96%; factors associated with higher mortality in the bivariate study were main disease rapidly and eventually fatal, diabetes, a situation of critical initial clinical severity, lung focus, complications, neutropenia and inadequate antibiotic treatment. The logistic regression study, the critical initial clinical severity, and the presence of complications were the variables associated with worse prognosis. We did not find significant differences in the evolution among the patients who received monotherapy and those on combinations of antimicrobial drugs against pseudomonas., Conclusion: Higher mortality of PAB is statistically associated to the situation of critical initial clinical severity and to the presence of complications; therefore, an early diagnosis and adequate treatment to improve the morbidity and mortality are recommended.