The study revealed that the isolation rate of group A streptococci in scarlet fever patients at the time of hospitalization did not exceed 68%. The isolation rate of these streptococci was greatly influenced by antibacterial therapy carried out before hospitalization. Under clinical conditions with intensive penicillin therapy group A streptococci were eliminated from the larynx on days 3-4. In 13% of children repeated streptococcal infection was observed 0.5-3 months after discharge from hospital.