BACKGROUND: Acute pharyngitis is a very common respiratory tract infection. Rapid antigen tests (RATs) that detect group A streptococci (GAS) have an advantage over conventional throat culture in determining the cause of acute pharyngitis quickly. The efficiency of RAT should be good enough to be used in the laboratory or in the clinics. METHODS: From October 2008 through February 2009, throat swabs were taken from 293 children with acute pharyngitis and conveyed to the Gyeongsang National University Hospital in a transport medium. Two swabs from each patient were inoculated onto a blood agar plate, then returned to the transport medium and stored at -20 degrees C for several months. After the samples were thawed at room temperature, the SD Bioline Strep A RAT (SD, Korea) was performed. RESULTS: The sensitivity, specificity, positive predictive value, and negative predictive value of SD Bioline Strep A compared with throat culture were 95.9% (95% confidence interval [CI]: 93.6-98.2%), 91.8% (95% CI: 88.5-95.1%), 95.9% (95% CI: 93.6-98.2%), and 91.8% (95% CI: 88.5-95.1%), respectively. CONCLUSIONS: The SD Bioline Strep A RAT kit can be useful as an alternative to throat cultures in the clinics for rapid diagnosis of GAS pharyngitis and for an early decision on the use of antibiotics.