Monarda didyma L. is a herbaceous perennial with the square stems and opposite leaves characteristic of herbs in the Labiate family. Monarda didyma L. is often used as a domestic medicine, being particularly useful in the treatment of digestive disorders. The leaves and flowering stems are antihelmintic, carminative, diuretic, expectorant, febrifuge, rubefacient and stimulant. Monarda didyma L. has twenty-six compounds in the essential oil, of which thymol, with smaller amounts of para-cymene, d-limonene, carvacrol, linalool, and hydrothymoquinone. A new method was used for the determining of the amount of separate flavonols by high-performance liquid chromatography. The flavonoids (rutin, hyperoside, quercitrin, luteolin, quercetin) were found in leaves and flowers of beebalm. The quantity of flavonoids was higher in flowers than in leaves of Monarda didyma L.