The effects of exposure to inhaled hydrogen-fluoride (7664-39-3) (HF) on lipid metabolism were investigated in male albino-guinea-pigs. One group of animals was exposed to 10 milligrams per cubic meter (m3) HF in a cylindrical plexiglass cage with an air turnover rate of 40m3 per hour for 8 hours. A control group was housed in the plexiglass cage under the same conditions, but without the gaseous HF. All animals were fasted overnight before blood samples were taken. Blood was collected by intracardiac puncture 30, 90, and 360 minutes after injection of 20 microCuries acetate per 100 grams. Livers were removed and homogenized; total lipids were extracted and then fractionated into triglycerides and free fatty acids by thin layer chromatography. Enzymatic methods were used to determine triglycerides and total cholesterol. Lipoprotein lipase was also measured. Plasma triglyceride and cholesterol concentrations were increased significantly in the experimental group, compared with control animals. There was also an increase in triglyceride values in the livers of the HF treated group. Lipoprotein lipase activity was decreased significantly in treated animals. The authors conclude that activation of hepatic triglyceride biosynthesis and inhibition of extrahepatic lipoprotein lipase activity may play an important role in plasma triglyceride accumulation.