We evaluated whether the adipose tissue content of 2 fatty acids of exogenous origin specific for ruminant fat, 15:0 and 17:0, reflect average long-term dairy fat consumption in free-living subjects. In 81 healthy women aged 30-77 y, we compared the relative content of these 2 fatty acids in subcutaneous adipose tissue with relative intake (% of total fat) based on four 1-wk weighed diet records made 3-4 mo apart and on a food-frequency questionnaire reflecting average past year consumption. The mean (+/-SD) daily milk fat intake was 20.0 +/- 9.1 g and fat from ruminant meat was 3.0 +/- 1.5 g according to food records, representing 29.2 +/- 8.9% and 4.6 +/- 2.2% of total fat, respectively. The intake of 15:0 and 17:0, which are 1.05% and 0.61% of milk fat and 0.43% and 0.83% of ruminant meat fat, was 0.22 +/- 0.10 and 0.15 +/- 0.06 g, respectively. Content of 15:0 and 17:0 in adipose tissue was 0.35% and 0.24% and relative dietary intake was 0.33% and 0.22% according to the food records and 0.32% and 0.21%, respectively, according to the food-frequency questionnaire. Correlation coefficients between 15:0 content in adipose tissue and intake from dairy foods only, according to food records, were 0.63 (Pearson) and 0.59 (Spearman); corresponding values for 17:0 were 0.42 and 0.45, respectively. Content of 15:0 and 17:0 in subcutaneous adipose tissue might be a valid biological marker of long-term milk fat intake in free-living individuals in populations with high consumption of dairy products.