Polymerase chain reaction and other DNA amplification techniques to identify elusive infections should prove to be an effective tool for the clinical and investigative rheumatologist. The capability to identify and characterize infectious organisms in fluids and tissue will enable early, specific, and potentially curative treatment. Similarly, the capability to exclude infection and differentiate postinfectious diseases will enable other therapies to control the inflammation. Understanding these molecular techniques will most certainly improve clinicians' effectiveness for diagnosis and care.