Abstract This chapter offers a comprehensive overview of valvular heart disease, focusing on the diagnosis, clinical presentation, and management of the most common native and prosthetic valve disorders encountered by adult care providers. It details the pathophysiology and hallmark findings of aortic stenosis (AS) and aortic regurgitation (AR) including systolic outflow obstruction and diastolic volume overload, respectively, as well as mitral stenosis (MS) and mitral regurgitation (MR), emphasizing their etiologies, murmur characteristics, and implications for left atrial and pulmonary pressures. The evaluation of prosthetic valve dysfunction, whether mechanical or bioprosthetic, includes recognizing complications such as thrombosis, pannus formation, endocarditis, and structural deterioration.