In the present study, we identified free amino acid (FAA) contents and chemical composition in four populations of Salmo trutta macrostigma living in Mediterranean region of Turkey. In addition, taste impacts of FAAs were evaluated by taste active values. Moisture, protein, fat and ash content were found in the ranges of 75.49 - 79.59%, 16.94 - 19.97%, 1.58 - 3.75% and, 1.39 - 1.56%, respectively. While the significant difference (p<.05) were found among the different populations in moisture, protein and lipid content, no significant (p>.05) differences in ash content was determined. Thirteen FAAs were identified from the muscle tissue of S. trutta macrostigma by HPLC. The Glycine was found predominant as followed by methionine, proline, and glutamic acid. Also, the amount of non-essential free amino acids in S. trutta macrostigma muscle were significantly (p<.05) higher than the essential amino acids. Glutamic acid, methionin, glycine, aspartic acid and lysine were of high taste activity values (greater than one), they had strong taste impacts on the mountain trout meat flavour.