1. Electrophoresis of pre-stained lipoproteins on acrylamide-gel gradients has been carried out on serum from populations of control subjects and patients with ischaemic heart disease. The technique resolves components intermediate in position and, by inference, in size, between very-low-density and low-density lipoproteins.
2. These central band components were found in 37% of a control population but the incidence varied with age and sex, being lowest in young males and highest in elderly males.
3. The incidence of central band components in patients with ischaemic heart disease was 64% (males) and 71% (females), and the difference between these figures and those for matched control subjects was highly significant. The intensity of central band components in the group with ischaemic heart disease was significantly greater than in the control group.
4. The presence and intensity of central bands show positive correlation with serum cholesterol and triglyceride values, but many patients showing the phenomenon have normal lipid values. Of patients with ischaemic heart disease 31% showed central band components and had normal lipid values.