Field experiment were carried out on the clay soil of the Experimental Farm, Faculty of Agriculture, Assiut University,Assiut in two consecutive  winter seasons 2007-2008 and 2008 -2009.The aim of this investigation was to study the effects of three planting dates and three seeding rates in cv. Giza 6 on yield and quality of onion sets un- der Assiut conditions. The obtained results indicated that the onion plants. Average bulb diameter increased significantly with earlier planting compared with later planting. Lower seeding rate gave significantly the biggest average bulb diameter. The authenticity bulb was obtained from planting on December 1st in the second sampling date (105 days).However, no true bulb was obtained from any planting date in the first sampling date (75 days)in both seasons. Lower seed rate (30 kg/feddan) significantly gave the truth bulb in both seasons.