An experiment under natural environment conditions was carried out to investigate the effects of ethephon and urea on tassel elongation and apical dominance. Zea mays cv. Piranão VF-2 plants were sprayed 38 days after sowing with ethephon (2-chloroethane phosphonic acid) 500 ppm, ethephon 500 ppm plus urea 2%, ethephon 1,000 ppm, ethephon 1,000 pmm plus urea 2%, ethephon 1,500 ppm, and ethephon 1,500 ppm plus urea 2%. The chemical accelerated tassel elongation as related to the control. Ethephon retarded apical growth and reduced plant height. The height of apical ear was reduced by ethephon or ethephon plus urea. The growth regulator reduced the length of apical internodes of the plants.