Drought and high temperature are the most important stressors that limit soybean crop productivity in the USA, particularly in the Midsouth. Glycine betaine (GB), a quaternary ammonium compound and an osmoregulant, was hypothesized to ameliorate effects of temperature and water stress on photosynthesis activity, growth, biomass accumulation and yield of many crops. Three (2 field and 1 pot culture) experiments were conducted during the 2004-2005 growing season. One field experiment consisted of larger field simulating the grower conditions in the Hills and Delta areas of Mississippi with three betaine treatments (0, 2 and 4 lb/acre) applied at flowering stage. Second field experiment consisted of two genotypes (DP 5989 and DP 5915RR), two timings of GB application (flowering and pod development) and three betaine treatments (0, 2 and 4 lb/acre). The pot experiment was conducted to understand physiology with three irrigation (100% well watered (WW); 60%WW; and 40%WW) and three betaine treatments (0, 2 and 4 lb/acre). Field experiments showed that timing of applications (flowering or pod-filling) did not significantly affect soybean yield. When averaged over years, timing of applications, and genotypes, GB treatments of 4 lb acre^-1 increased pod yields by 6 - 30%.  Soybean yields were increased by 6-15 and 6-34% during 2004 and 2005, respectively. Similar to the field studies, pot-culture experiments also showed an increase in pod dry weights by 8-15% across water stress treatments when compared to untreated plots. Increased photosynthetic rates and greater amounts of pigments were observed with the application of GB. The increased seed yields were associated with enhanced plant growth (taller plants with greater leaf area and biomass) and increased pod numbers. These results suggest that foliar application of GB at 2 to 4 lb/acre may be a simple and cost effective methodology to alleviate drought stress in soybean under rainfed conditions.