The Titertek-Enterobac-Automated System (TTE-AS, Flow Laboratories, Meckenheim, FRG) was evaluated for identification of members of the family of Enterobacteriaceae using a total of 816 bacterial strains obtained from stock cultures and clinical specimens. A comparison of the results of the TTE-AS kit with conventional methods was conducted. Identifications were classified as correct, not identified (two or more taxa possible, identification score less than 80%, supplementary tests for final identification were not performed), and incorrect. Correct identification results were further subdivided according to the level of identification by species or biotype: (a) greater than or equal to 98%, (b) 90% to 97%, (c) 80% to 89%. When compared with conventional identification results, the TTE-AS system correctly identified 95.3% (778 of 816 strains), 90.0% (734 strains) belonging to category (a), 3.4% (28 strains) belonging to category (b), and 2.0% (16 strains) belonging to category (c). For 18 (2.2%) of the remaining strains, the system generated the correct identification result, but with an identification level less than 80% (low discrimination results). 11 strains (1.3%) were misidentified and the system failed to generate identification results with 9 strains (1.1%). Reactions within TTE-AS were reproducible with an estimated probability of erroneous test results of 1.7%.