Assessing variability is fundamental to identify the most important traits in tef improvement program. The objective of the present study was to estimate variability, heritability and genetic advance based on ten morphological characters of tef (Eragrostis tef (Zucc.) Trotter). The experiment was conducted in 2012 main cropping season at Adet Agricultural Research Center using randomized complete block design with three replications. Analysis of variance revealed significant difference (p < 0.01) among treatments for culm length, plant height, number of primary panicle branches, days to heading, days to maturity, days to grain fill period, grain yield, biomass yield and panicle length and (p < 0.05) harvesting index. The maximum variability between phenotypic and genotypic coefficient of variation was recorded for number of primary panicle branch (15.5%, 10.3%) followed by panicle length (12.03%, 8.0%).High phenotypic coefficient of variation (PCV) was recorded for culm length (10.1%), panicle length (12.0%), and primary panicle branch (15.5%), grain yield (16%), biomass yield (11.0%), and harvest index. Similarly, high genotypic coefficient of variation (GCV) was observed for both grain yield (12.9%) and primary panicle branch (10.3%). Maximum heritability estimate were observed for days to maturity (93%), days to heading (86%), days to grain fill period (73.3%), culm length (72%), grain yield (65.2%) and plant height (60.3%). The rest quantitative trait exhibited moderate broad sense heritability values. The expected genetic advance as percentage of mean (GA%) was relatively high for grain yield (21.4%), day to heading (16.2%), number of primary panicle branches (14.1%), culm length (14.9%) and days to grain fill period (12.7%). High heritability with high genetic advance (as percentage of the mean) was observed for grain yield. High heritability coupled with moderate genetic advance as percent of mean was observed for day to heading, culm length, grain filling period, day to maturity and plant height which indicates that the characters can be improved through selection. Estimation of phenotypic correlation coefficient among traits indicated that there was positive and highly significant correlation between grain yield and culm length (0.84), plant height (0.82), days to heading (0.79), biomass yield (0.88), and harvest index (0.84). Grain yield had positive and highly significant genotypic correlation with plant height (0.71), culm length (0.62), days to heading (0.79), biomass yield (0.78), and harvest index (0.73) and also positively and significantly correlated with panicle length (0.51).Therefore, any improvement of these characters would result in a substantial increment on grain yield. Evaluation for variability of tef using conventional approach still could provide vital information but using contemporary molecular genetic analysis approaches such as mapping of quantitative trait loci using molecular markers is helpful to understand variability at molecular level, improve selection knowledge and arrive at more comprehensive conclusions. Repeating the experiment is advisable to better estimate environmental effects.