Clinical Background: The heart can cause kidney disease, and the kidney can cause heart disease. As an example of the first situation, we can mention dilated cardiomyopathies, which can lead to renal failure of the pre-renal type due to the state of renal hypoflow. As an example of the second situation, we can remember that renal failure is a risk factor for cardiovascular diseases, such as coronary heart disease, due to the acceleration in the process of atherosclerosis that it promotes. Epidemiology: In this chapter, we will address what we consider to be the two main aspects of the interrelationships between heart and kidney disease that are “cardiorenal syndrome (CRS)” and “chronic kidney disease (CKD) and coronary heart disease (CHD).” Challenges: For CRS, we discuss its epidemiology, types, pathophysiological mechanisms common to CRS types 1, 2, 3 and 4 and pathogenesis of CSR type 5. Treatment: For “CKD and CHD” we discuss the association of CKD and CHD in community-based populations, traditional risk factor in CKD, non-traditional risk factor in CKD, reduced risk of CHD in patients with CKD, statin treatment, hypertension treatment, anti-platelet aggregation therapy, treatment of CHD in patients with CKD and prognosis of CHDF in CKD patients.© 2021 S. Karger AG, Basel.