Utilization of rapid microbiologic methods could improve both the quality of patient care and help to reduce patient health care costs through more efficient patient management. Medically urgent situations such as meningitis, endocarditis, bacteremia, some soft tissue infections, ocular infections, and pneumonia in immunocompromised hosts are obvious areas for application of rapid methods. However, efficient management of outpatient infections such as group A streptococcal pharyngitis, bacteriuria, diarrhea, and sexually transmitted diseases could also benefit from rapid test results. Rapid methods for detection of slow growing or unculturable microorganisms represent a promising area for development of new test methodologies. Realization of the potential of various rapid microbiology tests, however, requires that several difficult questions be addressed. Acceptable test rapidity and accuracy must be established by concensus of microbiologists and clinicians. Moreover, new approaches to reduce total test turn-around time and novel means to facilitate physician use of rapid test results must be sought in the immediate future.