Field studies were conducted during 1985 and 1986 to study the effect of stage and rate of ethephon application on growth, combine-harvested yield, and yield components of three corn (Zea mays L.) hybrids at two densities. Ethephon was applied at four rates from 0 to 560g ha−1 at three growth stages: tassel elongation (TE ≥ 3mm), TE + 6d, and Ear elongation (EE ≥ 3mm). The greatest rate of ethephon decreased lodging by 85% in 1985 and 93% in 1986. Reduction in yield at the greatest rate of ethephon was 6% and 2% of the control in 1985 and 1986, respectively. Brace-root rating in 1986 was increased 20%, when comparing the greatest application rate with the control. In the same year, weight per seed was reduced 2%, which was equivalent to the percentage yield reduction. Plant and ear heights generally decreased in a linear fashion with increasing rate of ethephon. The growth stage at the time of ethephon application significantly altered all variables except grain moisture. Grain yield, seed weight, and lodging decreased as ethephon application was delayed. Decrease in seed weight probably caused the yield decrease with delayed application. Stages of application interacted with rate such that ear height was reduced less as ethephon application was delayed. The greatest rate of ethephon applied at the beginning of EE resulted in the best lodging control. However, reduction in lodging did not result in higher yield. Also, ethephon applied at the TE stage mainly affected elongation of internodes below the ear; at the EE stage, elongation of internodes above the ear was affected.