Formation of free amino acids was studied during ripening of 2 hard cheeses (Sbrinz, Gruyere) and 3 semihard cheeses (Walliser Raclette, Appenzeller, raw milk Tilsiter). Cheeses were examined periodically from day 1 or 8 (Gruyere) to day 546 (Sbrinz), 245 (Gruyere) or 130 (semihard cheeses). Results (tabulated for N fractions and individual free amino acids) showed that free amino acids increased at different rates in the different cheeses. Predominant free amino acids in all cheeses studied were glutamic acid, proline, lysine, leucine and valine. Glutamic acid was the main free amino acid in 4 of the cheese types, the exception being Walliser Raclette, in which leucine predominated. Content of water soluble N increased during ripening to approx. a quarter of total N in hard cheeses and to about 40-50 % of total N in semihard cheeses