This chapter reviews the clinical features, diagnostic challenges, and management principles of key cardiomyopathies encountered in hospitalized patients, focusing on dilated cardiomyopathy (DCM), hypertrophic obstructive cardiomyopathy (HOCM), and cardiac amyloidosis. DCM is characterized by ventricular dilation and systolic dysfunction, often presenting with heart failure symptoms. HOCM involves asymmetric septal hypertrophy causing dynamic outflow obstruction, frequently associated with exertional dyspnea, syncope, and arrhythmias. Cardiac amyloidosis results from extracellular amyloid protein deposition causing restrictive physiology, marked by diastolic dysfunction and signs of heart failure with preserved ejection fraction. This chapter emphasizes differentiating these entities through clinical clues, echocardiographic findings, cardiac MRI, and advanced imaging such as nuclear scintigraphy or biopsy in amyloidosis. Understanding these differences aids in tailoring treatment—ranging from medical therapy and device implantation in DCM and HOCM to targeted therapies in amyloidosis—and informs prognosis. Hospitalists are equipped with practical strategies for early recognition, appropriate diagnostic evaluation, and coordination with specialty care to optimize outcomes.