The main objective of this research was to evaluate fourteen oat (Avena sativa L.) landraces and cultivars for drought tolerance using several indices. The trials were conducted both under rain-fed and irrigated conditions for three growing seasons (2001-2004) in two locations in the Central Anatolian Region of Turkey. Biplot analysis based on the Spearman's rank correlation matrix revealed that the drought indices were significantly inter-correlated with each other and can be classified into four groups. The first group, reflecting stress tolerance index (STI), mean productivity (MP), geometric mean productivity (GMP), harmonic mean (HM), linear regression coefficient (b(i)), yield index (YI), rainfed grain yield (Ys) and irrigated grain yield (Yp) appeared to be the relatively high yielding genotypes (G3, G5, G1, G2, G14, G6, G13 and G4) with high drought tolerance. The parameter of superiority index (P-i) in the second group was able to distinguish the landraces G10, G11, G12, G9 and G7 with low adaptability and low drought resistant. The third group included yield stability index (YSI) had a negative correlation with mean grain yield under irrigated conditions referred to drought resistant genotype (G8) with low yielding performance.