C-reactive protein is an acute time-phase reactive protein with relatively low serum concentrations. Its concentration usually increases significantly when bacterial infection inflammation, tissue damage or postoperative period occurs. In contrast, viral infections do not change significantly. It is possible to determine at an early stage whether it is a viral infection or a bacterial inflammation. In contrast, ultrasensitive C-reactive protein is an indicator for monitoring cardiovascular and cerebrovascular diseases. It can be used as a sensitive indicator to determine tissue damage and is a biomarker for cardiovascular inflammatory lesions. If atherosclerosis, thrombotic disease or peripheral vascular tethering occurs, ultrasensitive C-reactive protein is significantly increased. It plays an important role in the diagnosis and prediction of coronary heart disease and peripheral thrombotic disease in stroke. It is considered to be the gold standard for cardiovascular disease risk assessment, whereas common C-reactive protein does not have this role.