In developing countries, outbreaks of acute hepatitis A virus (HAV) infection have a cyclic recurrence and almost 90% of children go through disease by the age of 10. Although the evolution of HAV is rarely severe, it can cause significant economic and social losses. In order to analyze clinical and biochemical characteristics of acute HAV reported diseases in Constanta county, South Eastern Romania, during the last pediatric outbreak, all cases of hospitalized children, less than 13 years old (n=578), mostly boys with residence in urban cities, were included. Cases were divided into 295 isolated cases, mean aged 6.939 years, and 283, mean aged 6.587 years, diagnosed in different foci of the outbreak. Clinical and biochemical features of an acute HAV outbreak in the foci children��s collectivities and families consisted in mild form of disease with frequent hepatomegaly, lack of jaundice and lower levels of aminotransferases and bilirubin.