Seed yields are often related to vegetative growth (2-4); however, excessive vegetative growth may result in reduced seed yield due to lodging (3). Therefore, it is important to investigate the utilization of growth-retarding chemicals (1) to prevent over-elongation and lodging. In this paper, we report the effects of three kind of growth retardants on development and yield of soybean plants. Materials and methods. Seed of soybean cultivar 'Nanbu-shirome' were planted on May 30,1980, and one seedling per pot was transplanted to 1/2,000 are pots filled with Ando soH (volcanic ash) 6 days after sowing. Fused phosphate, calcium carbonate, calcium superphosphate, potassium sulfate and ammonium sulfate were applied to each pot before planting at the rate of 25, 10, 5.9, 2.0, and 1.4 g, r.espectively. Growth retardants used were B995 (N-dimethyl aminosuccinamic acid), CCC (chlorocholine chloride) and BCB (bromocholine bromide). Aqueous sprays of B99S, CCC, and BCB (1,000 ppm) incIuding a wetting agent were applied to leaves on June 25 until these become thoroughly wet. City water containing a wetting agent was applied to control plants. On June 25, the fourth trifoliate leaf was just emerging. The second application of chemicals was made on July 1 at the concentrations of 5,000, 1,000, and 1,000 ppm for B995, CCC, and BCB, respectively. All the plants were barvested on October 6 and separated into sterns, podshells, seeds, and roots. Plant parts were dried at 70°C and weighed. Results and discussion. Although CCC and BCB treatments induced chlorosis (the limb parts of the blade turned pale green), eventually they became green again. The leaves of the plants treated with B995 became slightly frizzled and changed to a dark green color. The leaves remained frizzled, and the leaf color remained darker than that of untreated plants througbout the experiment. A reduction in main stern growth was evident in B995 treated plants two weeks after tbe first application and in all treated plants after 3 weeks. The most effective