Two field experiments were carried out at the experimental station of National Research Centre, at Shalakan, Kalubia Governorate during the two successive growing seasons of 2004/2005 and 2005/2006 to study the additioneffect of sulphur levels (0, 150 and 300 kg/fed.) and nitrogen source (cattle manure, compost, ammonium nitrate and ammonium sulphate)on growth, yield and bulb quality of onion plants cv. Giza, 20.                 Results show that the vegetative growth i.e. plant length, number of leaves, fresh and dry weight of leaves, neck and bulb diameter, bulbing ratio as well as fresh and dry weight of bulb as well as bulb yield and some physical and chemical characteristic (bulb weight, diameter and height as well as bulb content of TSS, N, P, K, total protein and total carbohydrate) were significantly increased by increasing the level of S-application.                 Results also clear that the vegetative growth characteristic and bulb yield and its quality recorded their highest values by using ammonium sulphate as nitrogen source, however, cattle manure gave the lowest values of vegetative growth and bulb yield.