Lyme borreliosis, a systemic disease, described as a new nosological unit as late as in 1976, has called for special attention in particular during the past few years. The author concentrated his attention on affection of the heart, and based on analysis of many publications in the world literature, he submits a review on Lyme carditis which comprises the clinical picture, diagnostic possibilities and treatment. In the conclusion he indicates possible ways how to investigate the disease the course and prognosis of which are the subject of open discussion.