Influenza and ARI intensity in Bulgaria has low during week No 53 (28.12.2009 -03.01.2010). The total incidence per 10, 000 population was 49,28 (during the week 52 the incidence was 58,25). From a total of 380,450 persons under surveillance, belonging to all age groups, a total of 1,875 ARI cases have been reported (during the week 52 they were 2,216). The incidence is highest in the age group 0-4 ys (234.22 per 10,000 population), followed by age group of 5-19 ys old (87.32 per 10,000). The incidence, higher than the country average, has been reported in: Montana (116.02) and Yambol (112.37).