The paper comprises the results of examination of the number of indicatory bacteria of pollution degree (TVC 20°C, TVC 37°C) and sanitary state (TC, FC, FS) in the water of the Kamionka, Maniówka, Wiatrołuża and Piertanka Rivers in the north area of Wigry National Park in 1996 and the number of these microorganisms taken to Wigry Lake. The investigations were carried out at 3 sites situated on the Kamionka River (in Okuniowiec, below a group of "huciańskie" lakes, before the tributary to Pierty Lake), at 2 sites situated on the Maniówka River (in Lipniak and before the mouth to the Wiatrołuża River), at 5 sites on the Wiatrołuża River (in Wiatrołuża, above and below the estuary of the Maniówka River, at the mouth to Królówek Lake, between Królówek Lake and Pierty Lake) and at 1 site situated on the Piertanka River (between Omułówek Lake and Wigry Lake). The obtained values of bacteriological indices of pollution degree and sanitary state were compared with the criteria of surface water purity estimation suggested in literature and their usefulness for recreation. The number of the examined indicator bacteria found in the present research shows a significant water pollution (II and III class of purity) of the examined rivers in the region of rural areas and the improvement of purity degree along the river course. There were found leakages of pollution from cesspools in the rural areas (it is seen by a significant number of FC in water of given sites) and flows from other arable-forestry-pasture-meadow catchment (which is expressed by a larger number of Streptococci than Escherichia coli) as a main source of water pollution of the examined rivers.