Primary cardiac tumors are rare. We report a case of lipomatous hypertrophy of the interventricular septum in a healthy, asymptomatic, 16 year old female, diagnosed initially by echocardiogram. Non contrast Computed tomography (CT) and Cardiac magnetic resonance imaging (CMR) were also performed to confirm the diagnosis of this rarely reported condition. Lipomatous hypertrophy of the interventricular septum is a rare form of benign cardiac tumor characterized by the proliferation of adipose tissue (fat) in the interventricular septum. This clinical entity has to be differentiated from cardiac lipoma which is a benign, encapsulated tumor. CMR helps is differentiating between the 2 conditions. As the lesion was neither causing compression of the ventricle nor obstruction to blood flow, she was managed conservatively and advised follow up.