We report a 22-year-old man suffering from exercise-induced rhabdomyolysis of both lower legs. The patient was admitted to our department for deep vein thrombosis. Clinical examination showed diffuse erythema, swelling, and pain on palpation of both calves. Ultrasonography revealed muscle alterations. Creatine kinase plasma levels were slightly elevated. Based on these findings and on the detailed history the diagnosis of exercise-induced rhabdomyolysis was made. Exercise-induced rhabdomyolysis is an important and potentially fatal disease. Although it is a rare differential diagnosis of deep vein thrombosis, it has to be taken in consideration in patients with muscle alteration visible on ultrasonography. Early recognition and appropriate treatment are of utmost importance for a good clinical outcome.