This research was carried out to determine stable genotypes and investigate genotype × environment interaction (GE) effects on the forage yields of 24 tall fescue genotypes (Lolium arundinaceum, syn. Festuca arundinacea Schreb.) across 14 test environments (combination of year, location and moisture conditions). The GGE biplot method was used to evaluate the phenotypic stability of forage yield in the studied genotypes. The GGE biplot analysis accounted for 75% of the G   GE variation. According to GGE biplot, in terms of performance, the genotypes were divided into two groups. The first group, with more than the average yield, included G20, G24, G04, G01, G22, G14, G10, G17 and G02. The second group included the remaining genotypes with below-average performance. From the seven foreign genotypes evaluated, G10 and G22 fell in the first group and the rest were clustered in the second group. In the first group, the performance of G24 (from Semnan province) was the most variable (the least stable), whereas the G20 and G14 (both from Isfahan province) were highly stable. In the second group, except for G08 and G16, the performance of genotypes was highly stable. The genotype G20 (from Isfahan province) had superior performance under all of the test environments, suggesting that it has a broad adaptation to the diverse environments. The results obtained in this study demonstrated the efficiency of the GGE biplot technique for selecting genotypes that are stable, high yielding, and responsive.