The effects of sepsis on lipid metabolism have not been clearly defined. This study was designed to observe the changes in adipose tissue lipoprotein lipase (LPL) and fatty acid synthetase (FAS) after administration of Escherichia coli bacteria. Male Lewis rats, weighing 245 to 270 g, were assigned to two groups and fed a powdered chow diet for 14 days. On day 14, one group was inoculated with E coli. Twenty-four hours later, both groups were killed by decapitation. Serum triglyceride levels were significantly elevated in the E coli-treated rats. Adipose tissue LPL and FAS activity was significantly decreased by 50% in E coli-treated rats compared with the control rats. These results suggest that the elevated serum triglyceride levels associated with sepsis maybe caused by a decreased rate of clearance of lipids from the blood and an increased rate of hepatic lipid synthesis.