Two diazotrophic bacteria, coded as A31 and A32, were isolated from roots of the lefvarietiesrnDZ-01-354 and DZ-01-196, respectively grown in pots on loam soil from Debrezeit. Thesernisolates were characterized to the generic level and further comparison with the description ofrnthe type cnltures Azospirillum lipoferum (ATCC 29707) and Azospirillum brasilense (ATCCrn29145). These comparisons showed that the two isolates closely resemble A. lipofernm .rnHowever, on the basis of some differences in biochemical characteristics, it was suspected thatrnthese isolates may be different strains of A. lipoferum.rnIn an attempt to investigate the effect of these isolates on the yield and nitrogen content of tef,rninoculation studies on pot grown tef plants was conducted. Root inoculation of seedlings of therntwo tef varieties with Iml sterile water suspension (107-10' colony forming units (cfu) Iml ) ofrnthese isolates produced significant (p < 0.05) increases in height, grain yield, total shoot andrnroot weight, root shoot ratio, total grain nitrogen and protein content of grains. Grain yieldrnincreases up to 11. 6 % and total nitrogen and protein content of grains up to 5.7 % over andrnabove un inoculated controls were observed.rnThe bacterial isolate A32 has performed better than A31 in promoting growth and yield ofrnboth varieties. Differential plant responses due to different bacterial treatments was found to bernsignificant (p < 0.05) for parameters as height, root shoot ratio and total nitrogen and proteinrncontent of grains on both varieties. Of the two tef varieties Dz-01-196 responded better thanrnDZ-O 1-354 to inoculation with either of the isolates as demonstrated in a higher percentrnincreases over the respective controls for most growth parameters The existence of a possiblernspecific interaction between host cultivar and bacterial isolate which governs plant yieldrnresponses was suspected. Finally, the potential role of Azospirillum inoculation of tef seedlingsrnon reducing fertilizer requirements was discussed.