Traditional methods of diagnosing onychomycosis, such as microscopy, histologic staining, and cultures, may not provide the clinician with documentation before initiating antifungal drug therapy. DNA technology now supplies the tools for increased sensitivity, speed, and accuracy in the diagnostic arena by allowing for the amplification, qualification, and quantitation of DNA. These techniques, already being used to identify many infectious agents, may soon be commonly applied to onychomycosis. This report reviews some of the DNA-based techniques that are currently being used to identify dermatophytes and their possible diagnostic use.