Lipomatous hypertrophy of the inter-atrial septum is characterised by fatty accumulation in the inter-atrial septum. Long unrecognised, it has been discovered anew by virtue of the use of transesophageal echocardiography. The authors report three cases, including one presenting as acute ischemia of the right lower limb. After studying the contribution of imaging techniques to its diagnosis, the authors consider the principal differential diagnoses of this condition.