RESUMEN
Variability in both the content and quality of essential oil was observed in herb and leaf drugs in dependence on the harvest cut height of lemon balm (Melissa officinalis L. cv. Citra). Three different cuts were carried out on the respective plants. The oil content in the herb was highest in the top third (0.13 % V/m), satisfactory in the herb including both the top and middle thirds (0.08 % V/m) and lowest in the whole herb (0.06 % V/m). The oil content in the leaves of the respective herbs was in the range 0.39 % - 0.14 % V/m (top third part - whole aerial part). The percentage of citrals, linalool and beta-caryophyllene in essential oil decreased in the basipetal direction, whilst the amounts of beta-caryophyllene oxide and citronellal increased in the same direction. Citrals (A and B): 55.79 % in the top third part of the herb, 48.46 % in the whole herb, 59.74 % and 56.87 % in the leaves from that parts, respectively. Similarly, beta-caryophyllene: 5.01 %, 3.87 %, 6.97 %, 5.13 %; beta-caryophyllene oxide: 17.19 %, 24.07 %, 15.64 %, 17.82 %; citronellal: 2.73 %, 5.51 %, 2.82 %, 6.44 %.