Dilated cardiomyopathy is a progressive disease of heart muscle, characterized by ventricular chamber enlargement and contractile dysfunction with normal left ventricular (LV) wall thickness. The right ventricle may also be dilated and dysfunctional. Dilated cardiomyopathy has a prevalence of one case out of 2500 individuals with an incidence of 7/100,000/year, and it is the third most common cause of heart failure and the most frequent reason for heart transplantation. DCM is an idiopathic disease and sometimes appear sporadically. In many cases, the disease is inherited and is termed familial DCM (FDC). FDC may account for 20-48% of DCM. Different forms have been identified based on patterns of transmission and characteristics of the phenotype, these include: autosomal dominant FDC without extracardiac manifestations; autosomal recessive FDC; FDC with X-linked transmission; autosomal dominant FDC with subclinical skeletal muscle involvement; autosomal dominant FDC with conduction defects; autosomal dominant left ventricular non-compaction; unclassifiable FDC with retinitis pigmentosa and hearing loss. Diagnosis of DCM is based on medical history, physical exam, blood tests, electrocardiogram (ECG or EKG), chest X-ray, echocardiogram, exercise stress test, cardiac catheterization, CT scan, and MRI. Genetic testing may also be available to identify abnormal genes. There are no therapies that can cure DCM; however, some therapeutic interventions treat symptoms, whereas others treat factors that affect survival. In some severe cases, heart transplantation is needed.