Patients with refractory heart failure comprise a very important subgroup of patients with congestive heart failure. Before assuming that this condition simply reflects advanced, perhaps terminal, myocardial dysfunction, potentially reversible factors should be sought carefully. We describe a 58-year-old Hispanic man with a diagnosis of idiopathic dilated cardiomyopathy who presented with symptoms of severe congestive heart failure, glossitis, and peripheral neuropathy. His hemodynamic profile was characterized by refractory low-output cardiac failure and decreased vascular resistance. Thiamine deficiency was documented by a high thiamine pyrophosphate effect. His clinical condition was quickly reversed with thiamine administration. This response to thiamine administration supports the diagnosis and indicates that thiamine deficiency may play an important etiologic role in the deterioration of cardiac function in some patients with congestive heart failure.