Abstract The effect of mineral fertilization on the composition of the essential oil from the leaves and flowers of Tagetes patula from Bulgaria during the flowering period (July-September) was investigated by GC/MS. The highest oil yield was obtained from leaves in July for N4P2K4 (0.63%) and the basic components were piperitenone (29.4%) and piperitone (13.5%). The mineral fertilization had no effect on the oil yield from the flowers. Regardless of the variant, it was found that the flower oils in July were rich in caryophyllene oxide (12.0-48.4%) and piperitenone (3.0-7.0%), while the oil composition in September was different.