Glucose or corn oil was given perorally to fasting, young healthy volunteers, and the time course of acute effects on lipoprotein lipase activity (LLA) in adipose tissue, plasma glycerol, triglyceride, insulin, and blood glucose levels was followed. After glucose intake, adipose tissue LLA increased rapidly, reaching a maximum of 80 per cent above initial level after 2 h. Plasma glycerol, reflecting the rate of lipolysis of depot lipids, decreased rapidly, temporally well correlated to the LLA changes. After corn oil intake no significant effect on any of the parameters studied was observed except for an increase in the plasma triglyceride level caused by the influx of dietary lipid.