According the literature atrio-ventricular blockade (AVB) is the most frequent and well-known symptom of Lyme carditis. Typical signs of complete AVB include fatigue, lethargy and syncope- Morgagni-Adams-Stokes syndrome (MAS). The authors present their results and experience with 5 patients selected from a long-term study (conducted between 1987 and 1998) comprising 58 patients who developed MAS. The authors tried to evaluate the changes especially in the cardiovascular system. They correlated the clinical state with ECG findings, as well as with the levels of the Borrelia burgdorferi antibodies. The following results were obtained: 1) all patients had typical syncope, 2) the clinical course was not complicated (except one patient who developed ventricular fibrillation), 3) two patients had frequent symptomatic and asymptomatic arrhythmia including chest pain and episodic rest dyspnea, 4) subjective difficulties (usually palpitations) correlated with ECG findings (Lown 3a, 3b). The authors also looked for any relationship between clinical difficulties and levels of antibodies. The results obtained with an early permanent pacemaker were less favourable than those reported in the literature. Despite early treatment 2 patients had repeated palpitations and ECG correlates during the next years.