Abstract: Cultivation of Ethiopian mustard, as an oilseed, requires genetic improvement which relies on its genetic diversity and interrelationships among traits. A study was conducted to determine the extent and pattern of genetic divergence and the interrelationships among agronomic traits of Ethiopian mustard genotypes using simple lattice design at Holetta Research Center, Ethiopia. Univariate analysis has shown significant variation among genotypes in most traits. Cluster and principal component analysis resulted in the formation of seven clusters and has shown the presence of substantial genetic diversity among the genotypes. Genetic distances among clusters were significant from which selection of parents may be made for crossing in order to obtain genetic recombination and transgressive segregants. 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 aggregate effect of individual traits contributed for the total variation and this was principally responsible for their respective cluster formation. Present investigation also showed that factors other than geographic diversity such as genetic drift, selection pressure, closeness in pedigree and environment may be responsible for differential grouping of genotypes. A correlation and path analysis study showed that seed yield per plot positively correlated with number of seeds per pod, number of seeds per plant and oil yield per plot. In this study, number of seeds per plant was found the most important component for improvement of the seed and oil yield of Ethiopian mustard genotypes.