Five field experiments studied the effects of high planting densities, ranging from 83,000 to 667,000 seeds/ha, on eleven soyabean cultivars. Germination rates ranging from 32 to 100% and averaging 76%, resulted in actual plant densities of 45,000 to 296,000 plants/ha. Bean yields of the four shortest and earliest-maturing (64–67 days) cvs (Wakashima, Shi-shi, Palmetto and Tai Tah Kaoh Siang 58) increased with increasing density, producing highest yields at the highest plant densities investigated (222,000–286,000/ha) but 7 taller cvs, maturing in 80–126 days (P2, C13, C21, P4, D5, T10 and C28), produced reduced yields with increasing density, the lowest densities investigated (45,000–83,000 plants/ha) giving the highest bean yields.