Guar (Cyamopsis tetragonoloba L.) is an annual legume and valuable industrial crop due to high galactomannan gum content in its seed, which could be a potential alternative food and feed crop in the arid and semi-arid regions of the world. The objective of this study was to determine genotype X environment interactions and yield stability of some guar genotypes to understand their adaptation to varying environmental conditions. In this study eight guar genotypes, including five introduced genotypes (Kinman, HFG-53, RGC-192, Brooks and DSP) and three from Sudan (GS9, GS7 and GS8), were evaluated under rainfed condition at four sites (Malit, Gadarif, Obeid and Jabel Kordofan) for two growing seasons (2017 and 2018) and at one site (El Fashir) in 2018 cropping season. The experiment was laid out in a Randomized Block Design with four replications and plot size of six rows, 6 m long and 0.40 m width. Combined analysis of variance for seed yield of the 8 guar genotypes tested in nine environments (combination of sites and seasons) showed mean squares of environments, genotypes and GEI (genotype x environment interaction) were highly significant. Genotype Kinman obtained the highest mean seed yield over the environments (780 kg/ha) followed by DSP (706 kg/ha) and GS8 (703 kg/ha). Stability parameters were estimated for seed yield using Eberhart and Russell’s stability parameters and Additive Main Effect and Multipli-cative Interaction (AMMI) analysis. Accordingly, GS8 (single stem) was considered as the most stable genotype followed by DSP (branched), while Kinman (branched) was found adapted to more favorable environments with the highest mean seed yield over all environments.