Twenty-one cases of sepsis by Acinetobacter calcoaceticus biovar anitratus occurred, ten in 1989 and eleven in 1990 (January-April). In this last year, there were nine cases with characteristics of an epidemic outbreak. It was noted that sepsis was predominant in males, babies of less than 2,500 g and less than 37 weeks of gestation. They were hospitalized in our Intensive Care Unit for different problems, but almost all had mechanical ventilation, parenteral nutrition and received antibiotics previously, being these risk factors the most important. Clinical and laboratory features were not different from sepsis produced by other microorganisms. It is important to remark the increased frequency of Acinetobacter calcoaceticus biovar anitratus as a nosocomial agent, but also his greater aggressivity and antibiotic resistance, all factors that produced an elevated mortality, eight of eleven cases. Finally, due to the adoption of several measures the epidemic outbreak was stopped.