The objective of the present study was to investigate the antihyperlipidaemic efficacy of Trachyspermum ammi (L) Sprague, seed (Ajowan) powder in albino rabbits. Hyperlipidaemia was induced with butter ad libitum and oral intubation of cholesterol 400 mg/kg body weight. Simvastatin, (Tablet survive ® ) was used as a synthetic cholesterol lowering drug. The results suggest that 2 g/kg T. ammi seed powder produced hypolipidaemic activity, rendering 49%, 53%, 71% and 63% reduction in total lipids, triglycerides, total cholesterol and LDL-cholesterol, respectively. However, at this dosage level 62% increase in the value of HDL-cholesterol was induced by T. ammi seed powder. Nonetheless, 0.5 g/kg and 1 g/kg T. ammi seed powder did not show antihyperlipidaemic activity.T. ammi seed powder at the rate of 2 g/kg and simvastatin (0.6 mg/kg body weight) were equally effective in treating hyperlipidaemia in albino rabbits. Moreover, this dosage level also significantly reduced the cholesterol content of liver tissue. It can be anticipated that the lipid lowering mechanism may involve enhanced removal or catabolism of lipoproteins, inhibition of HMG COA reductase, and/or inhibition of lysosomal lipid hydrolytic enzymes secreted by the liver.