A 30-year-old man was admitted to our hospital for left lobar pneumonia with septic shock. Acute left-sided heart failure became evident as sepsis developed. Echocardiography revealed diffuse severe hypokinesis of the left ventricle (LV) and a pulmonary artery catheter showed Forrester subset II hemodynamics. Along with amelioration of sepsis and decrease of the serumconcentrations of tumor necrosis factor-a and interleukin-6, LV hypokinesis improved. It is suggested that the patient's heart failure mayhave been due to functional depression of myocardial contractility resulting from a direct effect of the cytokines towards the cardiomyocytes, the socalled "septic myocardial depression". (Internal Medicine 42: 60-65, 2003)