The MicroScan Rapid Neg ID3 panel is designed for the identification of Enterobacteriaceae and nonenteric glucose-fermenting and nonfermenting gram-negative bacilli. We evaluated this panel for its ability to identify gram-negative non-Enterobacteriaceae bacteria. A total of 134 strains, representing 26 genera and 42 species, were taken from storage at -70(o)C, passaged three times before testing, and inoculated into the panels according to the manufacturer's directions before being inserted into a Walk/Away 96 instrument loaded with version 22.28 software. At the end of the initial 2.5-h incubation period, 89 isolates (66.4%) were correctly identified at a probability level of > or =85%. After additional testing recommended by the manufacturer was completed, another 11 isolates (8.2%) were correctly identified at probability levels of > or =85%. Twenty-five (18.7%) isolates were correctly identified after additional testing, but the probability levels were less than 85%. Two isolates were unidentified, and seven (5.2%) were incorrectly identified. The seven misidentified strains were not concentrated in any one genus. With an accuracy approaching 75%, this product may be used for the identification of the commonly isolated non-Enterobacteriaceae bacteria but may present problems in identification of other non-glucose-fermenting gram-negative bacilli.