The pharyngitis of EBV infectious mononucleosis may be exudative or nonexudative. Exudative pharyngitis is commonly confused with group A streptococcal pharyngitis, which is complicated further by the fact that approximately 30% of patients with EBV infectious mononucleosis have group A streptococcal carriage of the oropharynx. The unwary physician may incorrectly conclude that a positive finding on throat culture or rapid test for group A streptococci in a patient with infectious mononucleosis represents streptococcal pharyngitis.