During the past four years, the Dept. of Aerophysics and Aerospace Engineering conducted evaluations of five agricultural aircraft to determine their performance, handling characteristics, and modifications to improve their safety and economy. As a result, several modifications were made to the basic aircraft to improve its performance. Reevaluation of the modified aircraft's performance showed that these modifications were beneficial.The evaluations showed that the greatest impediment in obtaining increased safety and performance is usually the dispersal systems used to distribute seed, fertilizer, and chemicals. Some effort was devoted to designing improved dispersal systems with lower power requirements. Results of the evaluation tests are represented.