A fifteen-year-old patient, with no past medical history, was admitted to the cardiology department for dyspnea occurring at the effort. Physical examination of the patient showed no signs of cardiac failure, with a normal cardiac and pulmonary auscultation. Electrocardiogram revealed a sinus rhythm with tachycardia. Diagnosis of hydatidosis was suspected, and thoraco-abdominal magnetic resonance imaging was performed. It revealed a huge cyst occupying the posterior and the inferior wall of the left ventricle, without hepatic involvement.