Lipoprotein electrophoresis on paper was performed on plasma from 132 fasting healthy individuals in order to determine the frequency of pre-beta lipoprotein. In 31% a pre-beta lipoprotein zone was seen on the electrophoresis strips. By far the highest frequency was found in males aged between 40 and 70, and the frequency was as high as 60% in males aged 50 to 59. There was a positive correlation between serum triglyceride values and the occurrence of pre-beta lipoprotein. A pre-beta lipoprotein zone with a higher rate of mobility than that normally found was seen in a few cases.