Comparative studies were conducted on highland and lowland Swiss hard cheeses: L`Etivaz cheese made at 2 locations 1300-2100 m above sea level, and Gruyere cheese made at Posieux (600 m above sea level) and Montbovon (approx. 1000 m above sea level). Botanical composition of the pastures differed between the sites studied, but cheesemaking methods were similar, except that milk was heated on open fires in L`Etivaz but in steam heated vats in Montbovon and Posieux. All cheeses were ripened in the same cellar under identical conditions. Composition of the milk, cream and cheese was determined, together with rheological and sensory properties of the cheese. Highland and lowland cheeses showed differences in terpene, trace element and secondary metabolite composition attributable to differences in pasture composition. Other differences, especially in volatile compounds and free amino acids, were attributable to differences in microflora, cheesemaking methods, etc. Cheeses made by heating the cheese milk on an open fire contained smoke constituents such as PAH. Highland cheeses had more intense sensory properties than lowland cheeses