The research investigated the antioxidant and cytotoxicity potentials of four medicinal plants from the Lamiaceae family, including Marrubium vulgare L., Vitex agnus-castus L., Phlomis olivieri Benth., and Nepeta ucranica L. The study evaluated the extracts' cytotoxicity by analyzing the mitotic index in onion root tip meristematic regions and cell viability in green algae Dunaliella salina. The findings indicated that P. olivieri and V. agnus-castus exhibited more significant antioxidant potential, but compared to the other, N. ucranica showed the lowest potential. The mitotic indices in the onion root tip's meristematic region and vulgar aqueous extract decreased with some increase in the extract concentrations of all studied plants. Additionally, the number of cells in various mitotic phases decreased, whatever cells in interphase increased in the treatment, and D. salina experienced a decrease in the number of cells with an increase in extract concentration. The study also observed a decline in the number of cells in the algal suspension with growth in extract concentration, particularly when exposed to V. agnus-castus extract. However, medicinal plants with high antioxidant potential are used in prevention, and various treatments with caution are advised due to their observed cytotoxic effects.