This review compares automated systems of blood culture for the detection of positive bottles, excluding mycobacteria. The performance of different systems is influenced by several key variables, including volume of the blood sample, the use of resins, shaking to increase the recovery of aerobic microorganisms, duration of incubation and final subculture. The Bactec, BacT/Alert, BioArgos and ESP systems require further study and technical improvement. There is no single ideal system of blood culture, and combinations of two or more methods are likely to provide the best results.