In a collaborative study at two university hospitals, the recovery of microorganisms and the speed of detection of microbial aerobic growth by the Vital system (bioMérieux) and a diphasic conventional blood culture system were compared. The Vital system monitors each blood culture bottle every 15 minutes to detect inactivation of fluorescent suspended in the broth medium due to microbial growth. A total of 1086 comparisons were made between the two systems, yielding a total of 117 isolates. Microorganisms were recovered more often from the Vital aerobic bottles (p < 0.05). The Vital system detected 43% of the microorganisms within the first 12 hours of incubation whereas in the same time the conventional system detected only 5% of the microorganisms. The results demonstrate that the Vital system is a reliable, continuous monitoring, fully automated system and an attractive alternative to conventional blood culture methods.