Acute viral hepatitis A (HAV) is a benign self-limited disease, which does not become chronical and does not require obligatory hospitalization. It's an intestinal infectious disease with a dominantly fecal-oral way of transmission. Endemic epidemic appearance of this disease on the municipality of Prijedor, with a very high level of incidence, from the sixties of the 20-th century, has put the viral hepatitis among the priority problems of epidemiologic practice. During the period 1965-2007. in Prijedor there were 5707 registered cases of HAV contaminated people and three death cases. From 1990 it has been noticed an epidemiologic regression of HAV followed by its complete absence during the period 1997-2007. Studies of reasons of HAV regression have been conducted by a descriptive-epidemiologic method according to sex, age, ethnic affiliation, place of residence, seasonal appearance of disease, and the way of water supply. It has been determined that there is no statistically important differences among contaminated people according to sex, differences in other treated parameters correspond to the data from literature [1,2]. Seroconversion has been proved in 53 persons or 55,2% of tested people. Percentage of sero-positive people was 93,7% among people older than 60 years of age and 79,2% among the refugee population. Based on studies, the epidemiologic regression of HAV from the 90-ties of the 20th century, is explained by the fact that this disease appears in the interepidemic period, that there is a significant collective immunity of population with the HA virus, and the most important, the basic epidemiologic factors which contribute to the spreading of disease have been removed - the majority of population live in the urban and suburban areas where a hygienic water supply has been provided for. Also the customs and habits of population have been significantly changed.