Hyperlipidemia is an associated complication of diabetes mellitus. Many spices and herbs are known to be hypoglycaemic. Cuminum cyminum belonging to the family Apiaceae is widely used in Ayurvedic medicine for the treatment of dyspepsia, diarrhoea and jaundice. The present work was done to study the role of C. cyminum supplementation on the plasma and tissue lipids in alloxan diabetic rats. Oral administration of 0.25 g kg(-1) body weight of C. cyminum for 6 weeks to diabetic rats resulted in significant reduction in blood glucose and an increase in total haemoglobin and glycosylated haemoglobin. It also prevented a decrease in body weight. C. cyminum treatment also resulted in a significant reduction in plasma and tissue cholesterol, phospholipids, free fatty acids and triglycerides. Histological observations demonstrated significant fatty changes and inflammatory cell infiltrates in diabetic rat pancreas. But supplementation with C. cyminum to diabetic rats significantly reduced the fatty changes and inflammatory cell infiltrates. Moreover, C. cyminum supplementation was found to be more effective than glibenclamide in the treatment of diabetes mellitus. Copyright 2002 Elsevier Science Ltd.