This study was undertaken to investigate the effects of meal pattern on lipogenesis and activities of lipogenic enzyme in rats epididymal and mesenteric adipose tissues. A high fat diet was fed either ad libitum or in 1 meal during the last 3 h of the dark cycle for 4 weeks. Lipogenesis was measured as glucose conversion to total lipid and activities of glucose-6-phosphate dehydrogenase (G6PDH), 6-phophogluconate dehydrogenase (6PGDH) and NADP-malate dehydrogenase (ME) were determined by measuring NADPH production. Lipoprotein lipase (LPL) activity and serum lipoprotein concentrations were also measured. Meal-fed (3 h) rats had a decreased food intake, body weight and carcass fat compared with rats fed ad libitum. The serum triglyceride concentration of meal-fed rats tended to be higher than that of the ad libitum rats. However, there were no differences between meal-fed group and ad libitum group in serum concentrations of HDL-cholesterol, LDL-cholesterol and total-cholesterol. Rates of lipogenesis in both epididymal and mesenteric adipose tissues were significantly higher in the meal-fed group than that in the ad libitum group. In addition, meal-fed group showed higher G6PDH, 6PGDH and LPL activities in both epididymal and mesenteric adipose tissues, but exerted no significant effect on ME activity. These results suggest that meal-fed rats compared with ad libitum rats have marked lipogenic capacity, although such elevation probably does not result in increase in carcass fat concentration. Thus, meal-fed diet can be an important determinant of the alterations in adipose lipid metabolism.