The relationship between the fatty acid composition of subcutaneous adipose tissue and diet was estimated in 59 Dutch women aged 32-35 years. Food consumption was estimated by taking the means of nineteen 24-hour recalls administered over a period of two and a half years, August 1981-December 1983. Highly significant correlations were found between linoleic acid content of fat tissue and diet (r = 0.70) and also between the linoleic acid-to-saturated fatty acid (linoleic/S) ratio of fat tissue and diet (r = 0.62). This confirms the hypothesis that on an individual level the fatty acid composition of the adipose tissue is a valid index for the habitual dietary fatty acid composition of free-living adults. When using one 24-hour recall instead of the average of 19 recalls, the correlation coefficient between the linoleic/S ratio of the diet and that of the adipose tissue was substantially decreased. This demonstrates the weakening effect of the large day-to-day variation in within-person intake on the correlation between a short-term assessment of the nutrient intake of an individual and a biochemical indicator of long-term nutritional status.