The scientific basis for the statement that plants and their active constituents play an important role in the prevention of chronic and degenerative diseases is continously advancing. The object of the present study was to evaluate the effect of Hibiscus sabdariffa L. dried calyx ethanolic extract on the serum lipid profile of Sprague-Dawley rats. The rats were fed during 4 weeks with either a basal diet, containing high cholesterol (1%), cholic acid (0.25%), lard oil (10%), or a supplemental diet with H. sabdariffa extract at 5%, 10%, and 15% levels (SD(5), SD(10), SD(15)). Weight gain and faeces dry weight were both very significantly less (p <or= 0.01) in SD(10) and SD(15) groups as compared to the control group, as was food efficiency in SD(15). In the case of SD(10), food efficiency was only significantly lower (p <or= 0.05). Faeces dry weight in SD(5) however, was the only one found to be significantly higher (p <or= 0.05). Triacylglycerols and LDL levels were both significantly less (p <or= 0.05) in all groups (SD(5), SD(10), and SD(15)) as compared to the control. For total lipids, SD(10) and SD(15) showed significantly lower levels (p <or= 0.05), whereas very significant differences (p <or= 0.01) were observed in the case of SD(5). All groups had lower cholesterol levels compared to controls; however, only the SD(5) group was statistically significant (p <or= 0.05). No significant results were found in any group in the cases of either phospholipid or HDL levels. A hypothesis of hibiscus acid racemization, (+)-HCA to (-)-HCA, mediated by intestinal flora enzymes possibly explains the significant triacylglycerol decrease in all experimental groups. VLDL, the precursor of LDL, is composed predominantly of triacylglycerols, suggesting that the significant decrease in LDL is related to observed triacylglycerol synthesis inhibition. Five percent H. sabdariffa extract addition showed the best results in the reduction of serum lipids under study conditions.