Rapid anaerobe identification (MicroScan) panels (4 h) were evaluated both visually and by the AutoScan-4, a computer-controlled microplate reader. The results of both reading methods were compared with identifications obtained by the conventional (Virginia Polytechnic Institute) method. In total, 237 anaerobes were tested. Correct identifications were obtained for 166 strains (70%) by visual reading and 157 strains (66.2%) by the AutoScan-4. Supplementary tests resulted in 80.1 and 76.7% total correct identifications, respectively. Comparison of the two reading methods revealed complete agreement for 169 strains. Differences between the two reading methods were due to difficulties in reading specific reactions. This was especially true with the clostridial species. The performance of the MicroScan system in the identification of anaerobic bacteria appears comparable to that of other 4-h identification systems for anaerobes, but this system shows significant variance from the conventional system. Improvements in the trays and data base are required before the system can be recommended for routine use.