This study was carried out at Shandaweel Agricultural Research Station, Sohag Governorate, Egypt, during 2007/2008 and 2008/2009 seasons to estimate mean performance, genetic variability, heritability and genetic advance (GS%) of eight genotypes of onion. These genotypes were Shandaweel 1, Giza 6 Mohassan, Giza 20 Original, Sabeeni, Shandaweel Early, Giza 20 White Flesh, Giza White and Giza Red. The highest means of plant height, number of leaves/plant, plant fresh weight were obtained by Giza Red genotype in both seasons. The highest means of plant dry weight was obtained by Giza 20 Original and Giza 6 Mohassan in the first and second seasons, respectively. The earliest genotype in maturity was Sabeeni followed by Shandaweel Early and Giza White, While Giza 20 Original and Giza Red were the latest genotypes. Giza Red genotype had the highest average total yield/fed followed by Giza 20 Original. While Sabeeni genotype had the lowest mean yield. Giza 6 Mohassan attained the highest mean of marketable yield/fed, while Giza 20 White Flesh genotype showed the highest means of average bulb weight and remained bulbs%. The lowest means of culls yield/fed, double bulbs% and bolters% were obtained by Sabeeni genotype. Total soluble solids percentage (TSS%) was not significantly affected by onion genotype. Heritability in broad sense (H²_bs) ranged from 13.04 to 97.35%.  The highest estimate of H²_bs was obtained for culls yield followed by remained bulbs% and total yield. Percentages of genetic advance (GS%) ranged between 5.32% for bulbing ratio and 80.31% for double bulbs%. High Percentages of H²_bs along with high GCV% and GS% were observed for culls yield and double bulbs%. High percentages of H²_bs along with low GCV% and GS% were noticed for days to maturity and TSS%.