Soil organic matter content is low in most cultivated soils in Iran but the addition of organic wastes may improve soil physical, chemical and biological properties. One of the problems caused by using manure and compost is the high salinity and its effects on plant growth. The purpose of the present experiment was to study the effects of manure leaching on soybean (Glycine max L. var. Williams) seed properties. Treatments consisted of a factorial arrangement of three organic wastes (Esfahan's municipal compost, cow and sheep manures) in four levels (0, 1, 2 and 4 % on dry weight basis) and two leaching levels (leached or not leached) in a completely randomized design with three replicates. The findings of the paper show that compost and cow manure increased most of the nutrient concentrations in soybean seeds. But adding sheep manure just increased nitrogen and Mn concentration significantly. Application of cow manure increased seed number by 49%. Application of compost and cow manure increased seed yield by 51 and 54%, respectively. Leaching of compost and sheep manure reduced seed yield. The effect of leaching on the seed nutrients concentration was not consistent. It can be concluded that better results can obtain with fewer leaching ratios.