Six cases of bacteraemia in hospitalized patients, 5 with a depressed immune status, were caused by lactobacilli. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of whole-cell proteins and API 50 CH carbohydrate patterns assigned the causative agents to the species Lactobacillus rhamnosus, Lactobacillus curvatus, Lactobacillus delbrueckii subsp. lactis and Lactobacillus paracasei subsp. paracasei.