The relationships between fodder plants and the fatty acid composition of milk fat were studied in lowland (600-650m), mountain (900-1210m) and highland (1275-2120m) areas of Switzerland. Correlation coefficients have been calculated between the occurrence of plant families and species and the concentrations of groups of fatty acids in milk fats from the Mountains and Highlands regions, where the botanical composition of the pasture was more similar than in the Lowlands. Besides further contributing factors linked to the altitude in Mountains and Highlands (e.g. walking), the correlations indicate which plants could be responsible for the occurrence of the most abundant fatty acids in milk fat. (C) 2002 Elsevier Science Ltd. All rights reserved