The effect of various dosages of the extract of the thyme medicinal plant on the slaughter qualities and the chemical composition of the meat of broiler chickens has been studied. The preparation was obtained by the method of water-ethanol extraction followed by low-temperature drying at the Agroecologia research laboratory of the Kuzbass State Agricultural Academy. The scientific economic experiment with the duration of 40 days was performed with broiler chickens of the Hubbard ISA F 15 cross at the broiler farm. One reference and five experimental groups of day-old broiler chickens were formed, 37 chickens in each group. The chickens in the reference group received basic diet, while the broilers in the experimental groups additionally received thyme extract in the following daily dosages: the first — 2 mg/kg, the second — 4 mg/kg, the third — 6 mg/kg, the fourth — 8 mg/kg, and the fifth — 10 mg/kg of body weight. At the end of the studies, the positive effect of feeding thyme extract on the characteristics of anatomical dissection of broiler chickens' carcasses was found. In the third, the fourth, and the fifth experimental groups, no significant differences were found, compared to the reference group. By the results of dispersion analysis of the data, a significant effect of thyme extract on the contents of lysine, threonine, and methionine has been found by the amino acid composition of the meat of broiler chickens.