Abstract: A study was conducted to assess the extent and pattern of genetic variability of Ethiopian mustard genotypes with respect to eight seed oil quality traits in 36 Ethiopian mustard genotypes at Holetta Agricultural Research Center, Ethiopia. The experiment was laid out in simple lattice design. Univariate analysis of variance has shown that there was significant variation among genotypes in all traits. Multivariate analysis has resulted in the formation of seven clusters and has shown the presence of substantial genetic diversity for further selection and breeding. Genetic distances among most clusters were significant from which selection of parents may be made for crossing in order to obtain genetic recombination and transgressive seggregants. Genotype in cluster 7 was relatively the highest in oleic and the lowest in erucic acid in its seed oil. Likewise, genotypes in cluster 2 and 4 showed the highest erucic acid and the highest oil content in their seedsm, respectively. Apart from selecting genotypes from the clusters which have higher inter-cluster distance, within a cluster performance of genotypes should also be considered for a particular trait of interest. The cumulative effects of individual traits were responsible for differential grouping of genotypes. The present investigation also revealed that diverse geographic region, though important, it could not be the only index of genetic variations, in which selection pressure, environment and genetic drift may also be the cause.