This article reviews the use of diagnostic tests to guide management of adults with sore throats. Pharyngitis due to group A beta-hemolytic streptococci represents the major diagnostic concern in these patients. Organisms other than group A streptococci can cause pharyngitis, but their clinical importance and their diagnostic tests have not yet been established. For many years, physicians have used routine throat cultures to diagnose group A streptococcal pharyngitis. Rapid tests have recently been introduced that detect the group A streptococcal antigen on throat swab specimens. Because both tests have high sensitivity and specificity, the choice of tests may depend on test turnaround time. Rapid tests should improve management by decreasing both short-term morbidity and inappropriate use of antibiotics.