TBE virus remains one of major etiologic agents of encephalitis in Poland. In the beginning of 90-ties great increase of TBE cases was observed. In the years 1993-2002 there were TBE 1966 cases reported in Poland, while in białostockie/podlaskie voivodeship there were 871 cases. In years 1993 and 1996 111 TBE cases annually were reported in this region. The highest TBE incidence in this region was registered in years 1993 and 1996 - 15.9 and the lowest in 2001 - 3.4. In analyzed period of time mean TBE incidence in Poland varied from 0.69 to 0.26. TBE cases from białostockie voivodeship from years 1993-1998 stated 43% of all cases in Poland and from podlaskie voivodeship from years 1999-2002 states 46% of all.