Dilated cardiomyopathy is the most common form of cardiomyopathy and the second leading cause of left ventricular dysfunction with highly variable clinical presentation and prognosis. The clinical courses vary and are strongly heterogeneous, ranging from asymptomatic patients to those suffering from intractable heart failure or sudden cardiac death due to arrhythmias. Previous studies have reported a 10 years cardiovascular mortality up to 40% in developed countries, due to advanced heart failure or sudden cardiac death. However, the prognosis of dilated cardiomyopathy patients is variable and depends on multiple risk factors. This chapter provides a review of dilated cardiomyopathy with specific focus on the pathophysiological aspects and genetic etiology of the disease.