Plasma lipoprotein composition, plasma kinetics of autologous [I-125]HDL and the metabolism of iv administered radioactively labelled artificial chylomicrons were studied in postmenopausal women during a control period and after 4 months of oral estradiol-17-beta treatment (1 mg/m2 body surface per day). Drug treatment significantly raised plasma HDL-cholesterol levels (19%) in the fasting state and total apolipoprotein A-I (16%), but did not interfere with triglyceride, VLDL, LDL or apolipoprotein-B values. As compared with the control period, estradiol-17-beta administration significantly slowed down plasma [I-125]HDL clearance by about 82% and reduced the delipidation index of the injected artificial chylomicrons by 47% as a consequence of impaired plasma lipolytic activity.1256657661