St. John’s wort (Hypericum perforatum L.) was grown under different levels of UV-B radiation, with selenium (10mgl −1 Se applied by foliar spraying in the form of sodium selenate) or without foliar Se application. The different levels of UV-B radiation comprised an enhanced level simulating 17% ozone depletion, ambient level, and a reduced level of UV-B radiation. The concentration of Se in unsprayed plants was from 20ngg −1 to 120ngg −1 . The concentration of Se in the organs of plants foliarly sprayed with Se ranged from 1000ngg −1 to 12,000ngg −1 , the highest concentration being detected in plants grown under reduced levels of UV-B radiation. Foliar application of Se fertiliser is feasible and effective in St. John’s wort and results in Se-enriched nutritional supplements.