1073, either, cat? PREVALENCE OF STREPTOCOCCUS A TONSILLITIS AND RHEUMATIC FEVER AMONG CHILDREN IN ULAANBAATAR CITY B.Burmaa, D.Zulgerel, D.Bayarmaa Health Science University of Mongolia, UB, Mongolia During the 1960s, the incidence of acute rheumatic fever ranged from 23 to 55 per 100,000 urban children aged from 2 to 14 years in the United States.Currently, it is less than 2 per 100,000 with a prevalence of rheumatic heart diseases of less than 1 per 1,000 school-aged children. In the past, the attack rate of rheumatic fever caused by streptococcal infections was about 3% in military population and 0,3 % among school children. In the United states today, the attack rate may be much lower,but valid data are not available. In 1984 WHO committee of experts in massive prevention of cardiovascular diseases and struggle with them noticed that rheumatic disease morbidity decreased in developed countries, but the disease remains a main cause of cardiovascular disease mortality in population aged below 40 in most developing countries.The study was carried out among 400 school children aged 10-16 of Ulaanbaatar city in order to determine the prevalence of the streptococcal tonsillitis, rheumatic fever and cardiovascular disease cause by rheumatic fever by using questionnaire and streptococcus latex assay. Conclusion: We studied the pharyngotonsillities related with the B-hemolytic of A group among the children in school which is located in the center of Ulaanbaatar city. The prevalence of streptococcal pharyngotonsillitis was 15,08%. Because of insufficient contact to doctors ( 46.7 %) when they got streptococcal infection, large number of episodes in a year (43.3%), incomplete treatment of tonsillitis(40.0%) becomes inflamed and transferred to the chronic stage. The research among the school children of "ger" or tent district school to analyzing the streptococcal pharyngotonsillitis was 50.25%. The half of children in suburban district has a streptococcal pharyngotonsillitis due to the treatments insufficiently contact to doctor (53.5%) when they having sore throats and infecting of streptococcus.Also can be influenced to the suburban area, living condition, social level, and parent's education.