Ninety-nine tef genotypes collected from more than eleven major growing regions of Ethiopia were planted at Adet in a 11X11 row column design in the year 2017 and genotyped with twelve SSR markers along with six wild relatives at National Agricultural Biotechnology laboratory, Holetta to investigate the extent and structure of the genetic diversity of selected Eragrostis tef accessions. The spatial analysis based on eighteen quantitative traits showed that there is significant variation among the tested genotypes for all recorded traits except for first basal internode length. Moreover, the ranges of values and moderate to high (10-30%) genotypic and phenotypic coefficients of variations (GCV and PCV) for all traits except phenology and peduncle length (<10%) demonstrated the existence of wide diversity among the genotypes. Estimates of broad sense heritability and genetic advance as percent of the mean detected for grain yield and yield component traits ranged from 57-75% thereby suggesting the possibility of improving tef through direct and positive selection of the primary yield related-traits. Correlation and path coefficient analysis also detected that vigorous and tall plants with longer panicles were attributed with high grain yield and the superseding trait determining grain yield is plant height. The first five principal components (PCs) explained 85% of the total variation. Cluster analysis in the morphological study grouped the 99 tef genotypes in to five distinct classes consisting of one to 58 individuals. Whereas, all the cluster, PCo and structure analyses in molecular study grouped the 98 tef genotypes and six wild relatives into four distinct classes consisting of 13 to 47 individuals. The high number of alleles per polymorphic loci ranged from seven for CNLT 538 to 29 for CNLT150 with an average of 12.67, average polymorphic information content (PIC=0.82) and average expected heterozygosity (He=0.86) implies suitability and efficiency of simple sequence repeat markers to detect genetic diversity of tef. The low genetic differentiation and high gene flow between pairs of regions indicated by AMOVA and fixation index (Fst) revealed within population variation is higher than between population variation. Generally, the present study showed the existence of high genetic diversity with unstructured genetic pattern among the tef genotypes which implies the vitality of conserved tef germplasms at Ethiopian Biodiversity Institute and the impact of the seed exchange system on tef breeding activities in Ethiopia.