Iinfluenza and ARI intensity in Bulgaria was low during week No 37 (09.09.2013 - 15.09.2013) and the total incidence per 10,000 population was 24.40(during week No 36 the incidence was 21.67). From a total of 381 562 persons under surveillance, belonging to all age groups, a total of 931 ARI cases have been reported (during week No 36 the cases were 827). The incidence was highest in the age group 0-4 yrs (126.29 per 10,000 population), followed by age group of 5-14 yrs (55.24 per 10,000).