One hundred forty-seven clinical cultures comprising strains of Escherichia, Enterobacter, Citrobacter, Klebsiella, Proteus, Providenciae, Pseudomonas, Salmonella, and Shigella were identified by the use of Enterotubes and routine differential media. There was agreement in the results obtained by the two methods with 121 (82.3%) cultures. The most frequent disagreement was in differentiating between Enterobacter and Klebsiella with the Enterotubes because the Enterotubes did not contain ornithine. If ornithine had been present in the Enterotubes it is possible that comparable results would have been obtained using the two methods with 97.2% of the cultures.