Chickenpox is a common childhood infection caused by the varicella-zoster virus. Complications are rare. We report on a 15-year-old boy who developed myocarditis during a varicella-zoster infection. The patient presented with severe chest pain, examinations revealed significant ST-elevations in the electrocardiogram and elevated troponin T levels up to 690 ng/l. Echocardiography showed decreased left ventricular contractility without coinciding pericarditis. He remained haemodynamically stable on analgesics and aciclovir and was discharged nine days later with normalized echocardiography and troponin T levels.