Atherosclerosis remains the major cause of death and premature disability. Hyperlipidemia is the most firmly established and best understood risk factor for atherosclerosis . Nowadays, major drugs used for treatment of hyperlipidemia have several adverse effects. Herbal medications such as Garlic (Allium sativum) and Anethum graveolens are prescribed as antihyperlipidemic agents.
The medicinal uses of garlic have a long history . Recent studies have validated many of its useful properties, such as:
• Cancer-preventive actions [3-5]
• Stimulation of phagocytotic function of macrophages and lymphocyte proliferation 
Antimicrobial effects. In vitro, allicin, the main organosulfur compound of garlic, has demonstrated activity against gram-positive and gram-negative bacteria as well as fungi, protozoa, and certain viruses .
• The cardiovascular-protective effects of garlic have been evaluated extensively in recent years. In animal experiments, garlic extracts have been shown to lower plasma lipid and cholesterol in rats [[8,9], and ], rabbits , chickens , and swine . Moreover, a number of intervention studies have similarly shown that garlic significantly reduced plasma lipids, especially total cholesterol and Low Density Lipoprotein (LDL) cholesterol in humans [[14,15], and ]. Aside from the reported antiplatelet aggregation and antithrombotic action , garlic reduced blood pressure [[18,19], and ] and stimulated fibrinolytic activity [21,23]. It was reviewed that aged garlic extract contains antioxidant compounds and increase nitric oxide production and decreases the output of inflammatory cytokines from cultured cells. These data suggest that garlic may improve impaired endothelial function in men with coronary disease treated with aspirin and statin . Two meta-analyses of randomized, placebo-controlled human studies confirmed the hypocholesterolemic effects of garlic [24,25]. The analyses further detected that the extent of the cholesterol-lowering properties of garlic differed markedly from one study to another [24,25]. It was estimated from the five randomized clinical trials that hypercholesterolemic patients treated with garlic had a mean plasma cholesterol concentration that was 9% lower than that of patients treated with placebo . Silagy and Neil , on the other hand, concluded from the analysis of 17 human studies that plasma cholesterol concentrations of the subjects treated with garlic were 12% lower than those receiving placebo. Furthermore, the two analyses detected a wide range of decrease in mean plasma cholesterol concentrations (i.e., 6–53 mg/dl) among the studies. However, garlic supplementation has been shown not to decrease plasma cholesterol concentrations in human [[26,27], and ]. Although the reasons for the inconsistent observations are not readily apparent, it is worthwhile to note that garlic contains a variety of organosulfur compounds, amino acids, vitamins and minerals . Some of the sulfur compounds such as allicin, ajoene, S-allylycysteine (SAC), diallyl disulfide (DADS), S-methylcysteine sulfoxide, and S-allylcysteine sulfoxide may be responsible for the therapeutic properties of garlic . Animal studies have shown that garlic supplementation in the diet depressed the hepatic activities of lipogenic and cholesterogenic enzymes such as 3-hydroxy-3-methyl-glutaryl-CoA(HMG-CoA) reductase .
Anethum graveolens is another herbal medication with antihyperlipidemic effects. Administration of water extract of anethum graveolens leaves for 14 days can reduce triglyceride and total cholesterol levels by almost 50 % and 20 %, respectively .
Nowadays, there is wide spread belief among general public that garlic and anethum graveolens have beneficial effects on hyperlipidemia. This belief persuaded us to perform this investigation.