Total phenolic content and flavonoid concentrations in methanolic extracts obtained from Teucrium chamaedrys L. in five natural populations of the Balkan Peninsula and a garden population were investigated and compared. The above-ground parts of plants were collected during the flowering phase and the methanolic extracts were prepared. The total phenolic content of the extracts was determined using Folin-Ciocalteu reagent and expressed as gallic acid equivalent. The obtained values varied between 142.04mg GA/g and 265.91mg GA/g. The concentration of flavonoids was determined using AlCl3 and expressed as rutin equivalent. The obtained values ranged between 55.66mg Ru/g and 90.48mg Ru/g. The highest phenolic content was found in the plants collected from the mountain areas (Bulgaria, Serbia, Bosnia and Herzegovina) and somewhat lower content was found in plants from Mediterranean localities (Montenegro, Croatia). The lowest level was found in the extract obtained from the cultivated plant (Greece). The highest concentration of flavonoids was found in the plants from Mediterranean localities (Croatia, Montenegro), while the levels were lower in the other samples and ranged between 50 and 70mg Ru/ml. On the basis of comparative analysis, the plants collected at higher altitude localities were found to be richer in total phenolics, while higher concentration of flavonoids was found in T. chamaedrys from Mediterranean localities. A cultivar of T. chamaedrys had lower concentration of phenolics in comparison with natural populations. The results obtained in the analysis point out that the concentration of phenolics depend on the ecological properties of the plant habitats.