Abstract: The current study was initiated to find out the nature and magnitude of genetic variability for different traits in 12 maize genotypes using randomized complete block designs in humid tropics of Ethiopia in 2015. Analysis of variance showed that the mean squares due to genotype were significant at (p<0.01) for maturity traits, plant and ear height, number of row per ear, thousand kernel weights and grain yield per hectare, indicating the existence of sufficient genetic variability and the potential for selection and improvement of the traits. High phenotypic and genotypic coefficients of variations were obtained from number of ear per plant, ear diameter, grain yield per hectare, number of row per ear and ear length, indicating less environmental influence on the traits. High heritability estimates were obtained from all traits except anthesis-silking interval depicting the traits respond positively due to selection. Estimates of genetic advances as percent of mean at 5% selection intensity ranged from 4.68% for 1000-kernel weights to 78.95% for number of ear per plant.