The use of plants as herbal medicines has increased considerably in recent years, also increasing the interest of the population, health agencies, and pharmaceutical industries in ensuring the microbiological and physicochemical quality of medicinal plants and their derivative products. Among the methods currently used in the microbiological decontamination of plant materials, gamma radiation stands out as one of the most efficient techniques. However, due to the high energy of this type of radiation, plant material can be chemically altered, affecting its composition and biological properties. The species Solanum stipulaceum Roem & Schult (Solanaceae) is endemic and native to Brazil, widely used by the Brazilian population for therapeutic purposes, but still little studied chemically and pharmacologically. In this context, the effect of gamma radiation on the chemical composition of essential oils from the flowers and leaves of S. stipulaceum and on their antioxidant and antileukemic properties was evaluated.