In order to prevent late sequelae from an untreated streptococcal pharyngitis all patients with streptococcal tonsillitis/pharyngitis have to be treated with antibiotics, preferably penicillin. A correct diagnosis by clinical criteria is only achievable in 72% of patients with streptococcal pharyngitis. Additional criteria such as diagnosis by culture are, therefore, mandatory. Time is a major disadvantage of traditional culture methods. Slide agglutination tests show an acceptable sensitivity of 92% and a specificity of 93%. Due to the possibility of false negative test results, with consequent withholding of adequate antimicrobial chemotherapy, these test results should be used only as a valuable guide. Decision to administer an antibiotic should still be based on clinical criteria.