Dietary conjugated linoleic acid (CLA) from ruminant-derived foods may be potentially beneficial to health. The quantity of cis-9, trans-11 CLA and trans-10, cis-12 CLA in a range of UK foodstuffs (112 foods) was determined using triple-column silver ion HPLC. The cis-9, trans-11 CLA content ranged from 1·9 mg/g lipid (mild Cheddar) to 7·3 mg/g lipid (processed cheese) in cheeses, from 0·9 mg/g lipid (ice cream) to 3·7 mg/g lipid (double cream) in non-cheese dairy products, and from 2·9 mg/g lipid (Swedish meatballs) to 6·0 mg/g lipid (minced lamb) in meat products. cis-9, trans-11 CLA concentrations for chocolate and sweets ranged from 0·1 mg/g lipid (hot chocolate) to 4·8 mg/g lipid (buttermint). The trans-10, cis-12 CLA isomer was undetected or negligible in the food samples examined. To provide information about dietary cis-9, trans-11 CLA intakes in the UK, a study was performed to estimate the daily intake of CLA in a cohort of eighteen healthy volunteers (nine female and nine male; aged 21–60 years; mean BMI = 24·0 kg/m2 (sd 2·2)) with a 7-d weighed food record. This information combined with the CLA isomer contents of UK foodstuffs was used to estimate the daily intake of the cohort. The mean daily intake of cis-9, trans-11 CLA was estimated to be 97·5 (sd 73·3) mg/d. Due to its potential health benefits, it is important to determine the CLA content of food and dietary intake as these data will be useful in determining the role of CLA in health and disease.