Abstract: Optimum plant density of soybean varies with geographic location and variety. The present study was undertaken with a view to optimize plant density of two soybean varieties using equidistant planting patter to obtain higher yield. The experiments were conducted in three consecutive seasons viz., Rabi 2004-05, Kharif 2005 and Rabi 2005-06 at Mymensingh, Bangladesh with two soybean varieties G-2 and PB-1 and six plant densities viz., 20, 40, 60, 80, 100 and 120 plants m-2 established using an equidistant planting pattern of 22.4x22.4 cm, 15.8x15.8 cm, 12.9x12.9 cm, 10.0x 10.0 cm and 9.1x 9.1 cm, respectively. Seed yield increased with increase of plant density up to 80 to 100 plants m-2 depending on variety and season. The increase in plant density decreased yield components such as number of pods plant-1, seeds pod-1 and 100-seed weight as well as seed yield plant-1. The soybean seed yield was positively correlated with total dry matter and leaf area index. The present study concludes that the highest soybean yield could be possible with a plant density of 80-100 plants m-2 depending upon variety, season and related agronomic management options.