klorphological and isozyme diversity study of 47 barley (Hordeum vulgare L.) populationsrnthat were collected fi'om 11 regions in Ethiopia was undertaken for this study. Thernpopulations with number of individuals ranging fi'om 43 to 45 per population, which make uprna total of 2057 individual plants were evaluated for 16 quantitative and 14 qualitativernIIIO/phological characters. Isozyme analysis was conducted using three enzyme systems:rnesterase (ES1), asparatase aminotramjerase (AA1) and leucine aminopeptidase (LAP) forrnseven barley populations selected after clustering them on mOlphological characters. Proteinrnanalysis was determinedjar 47 barley populations based on the Kjeldahl standard procedure.rnSeveral statistical methods' such as mean, coefficient of variations, estimates of heritability,rngenetic advance, correlation coefficients, cluster analysis, chi-square test, principalrncomponent analysis, discriminant analysis, correspondence analysis and Shannon-Weaverrndiversity index (H) were lIsed to estimate the mOlphological variatiol1. Analysis of variancernshowed that there were highly significant differences between populations. In principalrncomponent analysis the first five principal components were contributed 85.5% of the totalrnvariation. Discriminant analysis revealed that 45 populations out of 47 (95.7%) wererncorrectly c1assjfied to their respective cluster. Correspondence analysis result indicated thatrnthe first five components or variables accounted for 89.15% of the total inertia while the firstrntwo axes retained 67.79% of the total inertia. The Shannon-Weaver diversity index (H') forrnindividual characters, populations, altitudinal classes and regions were estimated. Based 011rnthis, the H' value ranged ji'Oln 0 (monomOlphic) for awn colour and kernel cover to 1.0rn(highly polymOlphic) for flag leaf area. Region wise comparison displayed higher magnitudernof differences. The variation rangedji'Oln H'=0.56 for Hararge to fJ'=O. 71 for ShelVa, Arsi and Gojam. Among 11 regions, Shewa, Arsi and Gojam showed highest diversity index. Onrnaltitudinal base the highest diversity index (H'=0.74) was observed in altitudinal class ofrn2501-3000 m asl. The overall mean diversity index for ilie present Ethiopian barley wasrnestimated to be (H'=0.75). Phenotwic polymOlphism was observed for the esterase (EST)rnenzyme and there was no variatiol1 observed for Aspartate aminotlYlnsferase (AAT) andrnleucine aminopeptidase (LAP). Correlation between Sliannol1- Weaver diversity index ofrnqualitative IJlOl]J/lO/ogical c/wracfers (flld isozYlIlcs' vuiÂ·hilro/ls ,,,,,llOwed sign(flc(lnl positive andrnnegative association. When l' < 0.05 is used, the following character combinations showedrnsignificance. EST-l and Kernel colo III'; EST-3 and gillme hairiness; EST-4 and kernel colo III';rnEST-2 and lodging; awn colo III' and glume hairiness; and flag leaf area and lodging. Est-3rnand gil/me hairiness, and flag leaf (//:ea and lodging are the character combinations thatrnshowed a negative significant correlation. Protein analysis of 47 barley populations wasrnundertaken and the result showed highly significal1t differences between populations,rnaltitudinal classes and regions. The present study indicated that regions with high diversityrnindex (H') are more important for germplasm collection amlfor identification of suitable sitesrnfor in-situ conservation.rnKey words: Hordeum vulgare; Barley genetic diversity; MOIphological character; Isozyme;rnProtein