Matrix assisted laser desorption ionization time-of-flight mass spectrometry (MALDITOF MS) was investigated for the rapid identification of bacteria, either by comparison with archived reference spectra or by co-analysis with cultures of known bacteria. Bacteria were sampled from agar, mixed with the laser desorption matrix, air-dried, and introduced in batches into the mass spectrometer for analysis. In the first experiment, both bacterial strains that had been previously analyzed to obtain reference spectra and other strains that had not been analyzed were blind-coded and their spectra obtained. Those strains that matched reference spectra were correctly identified even when blind-coded. A second experiment involved coanalysis of reference strains and blind-coded strains under identical conditions; species-specific identification was demonstrated by comparison of spectra of the blind-coded strains with those of standards.