In a survey the authors deal with the metabolic role of the HDL and the HDL-cholesterol. Via several mechanisms (LCAT-substrate, esterification of cholesterol and transport of cholesterol, competitive LDL-inhibition) the HDL render possible the efflux of cholesterol from the vessels and its catabolism in the liver. HDL-cholesterol possesses a cardio-protective effect. As it was proved by epidemiological, clinical, angiographical and experimental studies, it is reduced in cardiovascular diseases. Its determination, in connection with the calculation of the LDL-cholesterol renders possible diagnostic and prognostic evidence concerning the coronary risk. For males the standard risk is in a HDL-cholesterol of 35-55 mg/dl (0.9-1.4 mmol/l) and for females of 45-65 mg/dl (1.2-1.7 mmol/l). A series of influence factors and diseases which are cited have influence on the HDL-cholesterol-concentration. By physical conditioning, change of nutrition, reduction of weight and different medicamentous measures it is increased.