Sorghum is among the most significant cereal crops of the world and used as a source of energy, protein vitamins, and minerals. Improvement in sorghum yield depends on the extent of genetic variability in the base population. The purpose of this study was to assess variation, traits interrelationships, expected genetic advance and heritability in advanced early maturing sorghum genotypes. Forty-nine advanced early maturing genotypes were evaluated on a 7*7 simple lattice design with two replications at Sirnika Agriculture Research Center. The analysis of variance indicated that mean square showed variation (P<0.001) for all of the examined traits except stalk diameter and panicle width. The grain yield of the studied genotypes ranged from 0.40 to 3.1t/ha with a mean value of 1.71 t/ha. The highest grain yield was observed from genotype ETSC-14252-4-1 (3.1 t/ha) followed by Melkam (2.8 t/ha), Girana-1 (2.8 t/ha) and ETSC-14236-7-2 (2.6 t/ha). The plant height of the studied genotype ranged from 119.6 to 248 cm with a mean value of 172.4cm. The days to 75% maturity was ranged from 119 days for Alene to 146 days for ETSC14230-1-1 with a mean of 134 days. The highest PCV and GCV values were recorded for harvest index (48.76%; 43.09%), grain yield (37.45%; 32.56%) and grain weight per panicle (32.81; 23.60%). Plant height, harvest index, panicle weight, and grain yield had high heritability associated with high genetic advance as percent of means. Grain yield had positive and significant phenotypic and genotypic correlation with harvest index (rp=0.77, rg=0.86), grain weight per panicle (rp=0.72, rg=0.78), panicle length (rp=0.35, rg=0.36) and individual panicle weight (rp=0.24, rg=0.28). Path coefficient analysis showed that harvest index, above-ground biomass and grain weight per panicle had high to a moderate positive direct effect on grain yield at genotypic and phenotypic levels. The hierarchical cluster analysis grouped the sorghum genotype under four clusters. Based on the quantitative trait data, the genotype ETSC-14252-4-1 (3.1 t/ha) and Melkam (2.8 t/ha) were found to be superior for grain yield. Therefore, these genotypes could be utilized in a further breeding program for developing better performing varieties. Keywords: coefficient of variation, genetic advance, heritability, path coefficient, principal component and sorghum 1 Chapter 1. INTRODUCTION 1.1 Background