The experiment was carried out to assess the extent and patterns of genetic variability of Ethiopian mustard land races in relation to topped plant seed yield and its related leafy vegetative traits at Holetta Agricultural research Center, Ethiopia. Information on the leaves of morphological traits of Ethiopian mustards as a leaf vegetable crop is lacking specifically that of time of defoliation to get dual purpose of the crop (leaf and seed). Therefore forty nine genotypes of Ethiopian mustard land races collected from different agro ecologies were evaluated for agro morphological traits in order to assess the genetic diversity that exists among these materials. The experiment was carried out in a simple lattice design. Univariate analysis of variance showed that there were significant differences among genotypes for leaf length, Length of Petiole, leaf width and leaf area traits but seed yield per plant leaf topped at 40^th, 50^th and 60^th growth stages of days of topping, leaf weight per plant topped to these similar days of topping and number of intact leaves at flowering showed non-significant differences. The significant difference indicates the existence of genetic variability among the accessions which is important for improvement of these traits. Average weight of 2.7g of seed yield per plant of defoliated could be attained by utilization of leaves in the 50^th day of growth stage of topping. Multivariate analyses resulted in the formation of four clusters and have shown the presence of substantial genetic diversity among the genotypes. The present study revealed the presence of considerable variability among genotypes for leaf length, Length of Petiole, leaf width and leaf area traits except seed yield per plant, leaf biomass per plant topped at 40^th , 50^th and 60^th growth stage days of topping and number of intact leaves at flowering. The significant difference of results indicates that the presence of good opportunity to improve these characters using the tested genotypes.