During 1988-1992 the hygiene service of the West Bohemian region received 1,954 notifications of Lyme borreliosis (LB), incl. 48.5% confirmed by serological examination. Among the affected systems the skin, joints and the nervous system predominated. The most frequently reported vector were ticks which alone accounted for 57.8%. Contrastly to tick-borne encephalitis, the disease was detected in all districts of the region and in all age groups. The highest morbidity was recorded in women in the age bracket of 45-64 years.