Some properties of very low density lipoproteins were studied under conditions causing an increase of their concentration in blood plasma. Content of high molecular apolipoprotein B and low molecular lipoproteins were estimated after fractionation using column chromatography and selective precipitation with tetramethylurea. In 216 men (40-59 years old) with hypertriglyceridemia the increase in content of particles of very low density lipoproteins was accompanied by simultaneous alteration in their composition in blood plasma: content of low molecular polypeptides, triglycerides and cholesterol was increased per a weight unit of apoprotein B. At the same time, the absolute concent of apoprotein B and of low molecular apoproteins of very low density lipoproteins was increased in blood plasma. The most distinct alteration in the ratio of apolipoproteins to very low density lipoproteins was observed, if content of testosterone--activator of lipoprotein lipase--was decreased in blood plasma.