Cardiac rhabdomyoma can be subclinical or have a fatal presentation according to the onset age and involving the site, size and degree of invasion. Although most rhabdomyomas become smaller with time, emergency intervention is indicated when severe obstruction induces hemodynamic instability. There is no recorded report of spontaneous resolution of huge symptomatic cardiac rhabdomyoma causing left ventricle inlet obstruction. In this report, we describe a case of spontaneous regression of large cardiac rhabdomyoma (20.5 X 15.6 mm) presenting as severe left ventricle inlet obstruction occupying 75-90 % of the mitral valve annulus in a neonate with tuberous sclerosis. Although the cardiac rhabdomyoma can be huge enough to induce LV inlet obstruction, conservative treatment without aggressive surgical intervention can be considered if the hemodymic condition does not deteriorate.