Among cardiac manifestations of Lyme disease, pericardic involvement, as the main symptom, seems to be exceptional. We report two cases of pericarditis with typical clinical features. In both cases, pericarditis was the only clinical sign of the disease. Diagnosis was based on significant high serological antibodies levels with no evidence of any other etiological factor. Penicillin was administered and lead in one case to negativation of the serology. As cardiac involvement can occur without any preexisting cutaneous lesion, the frequency of pericardic involvement in Lyme disease is certainly underestimated.