We herein describe the successful treatment of a patient with possible Legionella pneumophila serogroup 6 infection complicated by pneumonia and myocarditis. A 32-year-old man presented with a five-day history of cough, dyspnea and chest pain. Chest radiography revealed patchy opacities in both lungs suggestive of bilateral pneumonia, and a urinary antigen test for Legionella pneumophila was positive. After admission, the patient developed congestive heart failure due to pathologically confirmed myocarditis. He was successfully treated with minocycline, macrolide, steroids and noninvasive positive-pressure ventilation (NPPV). He eventually recovered with a normalized cardiac function. L. pneumophila serogroup 6 was isolated from the bathwater in the patient's home.