Hypothyroidism presenting with classic signs and symptoms is generally easily recognized. Less often, patients with hypothyroidism may present with symptoms and laboratory abnormalities suggestive of cardiovascular disease. In this article, we describe six such patients. Hypothyroidism was suspected when creatine phosphokinase (CPK) levels were persistently elevated. The diagnosis was confirmed by thyroid function tests, and thyroid hormone therapy resulted in resolution of symptoms and CPK elevations. Persistently elevated CPK levels associated with cardiovascular symptoms but without demonstrable myocardial damage should prompt consideration of covert hypothyroidism.