The paper presents the results of studies on the degree of pollution and the sanitary-bacteriological state of pelagic waters of Lake Wigry in northeastern Poland, 1994-1996. Thirteen sampling stations were selected in the most characteristic points of the lake. TVC 20°C and TVC 37°C were used as indicators of pollution, while TC, FC and FS served as indicators of the sanitary state. Pelagic waters in the north part of Lake Wigry showed a higher degree of pollution than waters in the middle and southwest part. As regards the north part, less polluted were Zadworze and Wapiennica bays, as was the middle point of this part, while Hanczanska Bay was more polluted than the other stations. Water in the middle part of the lake (stations Rosochaty Rog, Wysoki Wegiel, Zatoka Jastrzebia, Zatoka Bielanska) and in the southwest part (Plos Bryzglowski, Zatoka Slupianska, Zatoka Wigierki, Zatoka Uklei) was of good quality, showing exceptionally slight symptoms of pollution.