Serum cholesterol, triglycerides and their fractions in high density (HDL), low density (LDL) and very low density (VLDL) lipoproteins were measured sequentially in fasting patients on continuous ambulatory peritoneal dialysis (CAPD) who entered a prospective study. Of the 30 who entered, all have been followed to 3 months, 24 to 6 months and decreasing numbers to 18 months. Serum total cholesterol, VLDL cholesterol, total triglycerides and VLDL triglycerides all rose significantly during the first 6 months and VLDL cholesterol has remained elevated to 18 months. Changes in other fractions have been insignificant or inconsistent. 1 patient has developed angina. No associations were found between use of high dextrose fluid, weight gain and hyperlipidemia, probably because of consistent practice between patients. Our results confirm the adverse effect of CAPD on serum lipids and the need for dietary modification but are broadly similar to the changes that have been observed during regular hemodialysis.