The antihyperlipidemic property of aqueous celery extract was studied in rats. Two groups of Wistar rats were fed a high fat diet for eight weeks to induce hyperlipidemia. One group was supplemented with aqueous celery extract in the diet while the other group served as control. At the end of the experiment, a significant reduction was found in the serum total cholesterol (TC), low density lipoprotein cholesterol (LDL-C), and triglyceride (TG) concentrations in the celery-treated rats. However, the concentration of hepatic TG was significantly higher in the celery-treated group than in the control group. Hepatic triacylglycerol lipase (HL) activity was found to be significantly lower in the celery-treated rats while the reverse was observed for the hepatic microsomal P450 content. Analysis of an ethereal extract of the aqueous extract of celery by thin layer chromatography (TLC) with two different solvent systems showed that the extract did not contain 3-n-butylphthalide (BuPh), a unique compound in celery that has previously been reported to have lipid-lowering action. Our study indicates that other active principle(s) could be responsible for the observed effects of aqueous celery extract on serum and hepatic lipid levels.