We describe a case of progressive arrhythmia and heart failure combined with neurological symptoms that was resistant to conventional cardiological treatment. The outcome of a serological analysis was Borrelia IgG on a level consistent with chronic Lyme Disease. Antibiotic treatment with doxycycline resulted in complete remission of all cardiological symptoms. This case demonstrated Lyme Disease to be a potential factor in the pathogenesis of myocarditis as suggested by international publications.