A 51-year-old man presented with progressive tiredness, proximal muscle weakness, hair loss and weight gain for months. The patient showed mild pretibial myxedema and dry skin. Laboratory findings revealed strongly elevated cardiac enzymes as well as marked hypothyroidism.The electrocardiogram, echocardiography, abdominal sonography and chest X-ray were unremarkable. Thyroid ultrasound demonstrated features of Hashimoto thyroiditis.The findings supported the diagnosis of an overt hypothyroidism with myxedema and rhabdomyolysis. After starting levothyroxine and volume substitution laboratory parameters and clinical condition slowly normalized.Severe overt hypothyroidism may rarely present primarily as myopathy with myositis and cardiac involvement.