Benzyl adenine enhanced stomatal opening in isolated epidermal strips of Commelina benghalensis and Tridax procumbens. The stimulation was maximum at a concentration of 5 × 10-5 M BA. But kinetin had no remarkable effect on stomatal opening. The activity of benzyl adenine was observed over a narrow range of concentrations, from 10-5 M to 10-4 M. The increase in stomatal aperture was more pronounced in Commelina than in Tridax. Presence of benzyl adenine in the medium prevented the stomatal closure expected from abscisic acid and could reverse considerably the stomatal closure induced earlier by abscisic acid. It is felt that the balance between abscisic acid and cytokinins can possibly control the stomatal aperture effectively.