Objective An 80 years old man,suffered from cardiopulmonary arrest during swimming.After successfully cardiopulmonary resuscitation,he was sent to a hospital.After examination and inspection,he was diagnosed as cardiopulmonary arrest,aspiration pneumonia,hyperlipidemia,high level of creatine kinase.We prescribed a statin for the hyperlipidemia,but the level of creatine kinase was higher and higher.Finally he was diagnosed as hypothyroidism and lung cancer.We considered that severe weakness may be the reason of cardiopulmonary arrest in swimming pool.