Lyme disease is a multisystem infectious disease caused by the spirochete Borrelia burgdorferi. A steady increase in the number of cases is noticed both in Poland and Europe. Cardiac involvement in the course of borreliosis is relatively rare. It is estimated that it concerns about 0.5-10% of patients with Lyme disease. Cardiac involvement generally occurs in the early phase of illness. The most common manifestation of Lyme carditis are transient conduction abnormality, arrhythmias, myocarditis and pericarditis. The basic method of treatment Lyme carditis are antibiotics. The clinical course is usually benign. In most cases a complete recovery is observed. However, in a small proportion of patients dilated cardiomyopathy may occur. Furthermore, death from Lyme carditis has been reported. Lyme carditis remains a real diagnostic and therapeutic challenge for clinicians. Factors that can make the diagnosis difficult are: atypical clinical picture, negation of tick bite, the absence of erythema migrans, onset of symptoms outside the period of tick activity and negative serological results in the initial stage of the disease.