In Belgium, important regional differences in mortality exist which have been linked to differences in dietary consumption patterns.To study regional food consumption in Belgium, sales data of 103 spreading and cooking fat products in 110 branch stores of a major supermarket chain (Colruyt) for 12 months (1991-92) were analyzed.Sale of more ordinary and polyunsaturated spreading margarine and of more polyunsaturated low-fat spread in the north in combination with a greater sale of butter and dairy low-fat spread in the south resulted in a P/S-ratio of 0.99 in the north vs. 0.40 in the south (p<0.001) and a U/S-ratio of 1.93 vs. 1.10 (p<0.001) for spreading fats. The P/S- and U/S-ratios of cooking fats were lower in the north (ns). Mortality data correlated positively with the sale of butter and dairy low-fat spread and negatively with sales data of spreading margarine, polyunsaturated spreading margarine, and polyunsaturated low-fat spread (all p<0.001).Sales data from supermarket chains provide useful information on regional fat consumption and offer interesting perspectives of trends over time.