I started my research on hypertension and metabolic syndrome in 1947 in the 2nd Department of Internal Medicine, Sapporo Medical College. My main research theme focused on the epidemiology, pathophysiology, diagnosis and treatment of hypertension (particularly essential and secondary hypertensions). As part of my research, I clarified the role of renal kallikrein-kinin and renin-angiotensin systems for the etiology of hypertension by using a highly specified and sensitive radioimmunoassay for bradykinin and angiotensin II. Moreover, I performed comprehensive studies to investigate the role of epidemiology, pathophysiology, diagnosis and treatment of metabolic syndrome. In this review paper, the details of these studies are introduced.