The LEOPARD syndrome is a rare autosomal dominant, multisystem disease involving the skin, skeletal and cardiovascular systems. Echocardiography including stress testing was used in a patient with LEOPARD syndrome and recurrent syncope to reveal the hemodynamic relevance of a giant aneurysm of the interventricular membraneous septum ballooning into the right ventricular outflow tract. This case impressively underlines the vital necessity of dynamic testing particularly in patients with symptoms during exercise even if these symptoms might be addressed to other findings.