Because of the contemporary significance of gram-negative, nonfermentative bacteria as etiological agents, a simple, rapid determinative system is essential. Therefore, an accurate, reproducible, and an inexpensive micromethod for the identification of these organisms has been developed. Included in this system are twenty-five biochemical tests. Carbohydrate utilization is demonstrated by modification of Otto and Pickett's formula for oxidative attack and assimilation of carbon sources, while the other substrates are modifications of commercially available products. Inoculation is a two-fold procedure into a plastic multicompartmented tray with wells containing 100 micro liters of each substrate. Initial inoculation yields 10(5) colony forming units per well. The carbohydrates are supplemented with an additional 50 micro liters of a 1 X 10(11) saline suspension of organisms. Reactions are read after a maximum incubation of 48 hr at 35 C. The results obtained with the identification of 124 strains of nonfermentative bacteria utilizing a conventional media schema as suggested by the Center for Disease Control and the micromethod system demonstrated the high reproducibility and correlation achievable with this rapid and economical microtechnique.