A 35-year-old patient previously operated when a child for right ventricular (RV) rhabdomyoma was submitted to cardiac magnetic resonance (CMR) that showed a dilated RV and a small contractile cavity in the inferior left ventricular (LV) wall suggestive for diverticulum. This report shows the first description of a simultaneous evidence of LV diverticulum and previous rhabdomyoma, and furthermore highlights the important role of CMR for an easy detection of this congenital abnormality.