A Danish family consisting of 80 persons, 72 between the ages of 3 and 70 years, was examined for the presence of primary hyperlipoproteinaemia (HLP), resulting in the finding of types II A (8 cases), II B (4 cases), III (2 cases), IV (5 cases), and V (2 cases). The pedigree of the family is presented together with lipid data and HLP type. Five cases of the so-called ‘sinking pre-beta midband’, which can often be correlated to ischaemic heart disease, have been found using polyacrylamide gel electrophoresis (PGE); two of these subjects had arteriosclerotic disease, one had uratic arthritis, while the other two were normal. A comparative evaluation of the results of electrophoresis should be considered of greater importance when studying families, rather than individual persons, inasmuch as intra-familial lipid patterns appear to occur with a positive correlation to at least serum cholesterol. Continued observation will probably reveal a lipid abnormality characteristic for the family even though according to the reference material available it must be considered as nor