Six widely used commercial systems for Enterobacteriaceae identification (API 20 E, API 10, Enterotube, Enterotube II, Micro-ID and Minitek) were evaluated at the same time by testing 611 organisms. Conventional media were used for comparison. API 20 E, Enterotube II and Micro-ID were highly accurate and identified about 91% of the strains to the species level. The remaining organisms required additional tests and only a small minority was misidentified. Percentages of correct identification to the species level were 87.2 for Enterotube, 74.9 for API 10 and 67.1 for Minitek. Enterotube, Enterotube II and Micro-ID were, in our hands, the easiest systems to operate.