Lyme borreliosis is a disease commonly found in humans. Here we report the case of a young, healthy girl presenting with symptomatic first- and second-degree atrioventricular blocks secondary to cardiac myocarditis. The disappearance of the conduction anomaly after antibiotic treatment confirmed Lyme disease before the results from the serology. Therefore, when a healthy, young person suddenly presents with an atrioventricular conduction block, physicians should consider a diagnosis of Lyme disease
