A field experiment was conducted at the Agricultural Research Station, Sids, Beni Sweif Governorate during two successive seasons (1995-1996 and 1996-1997) to study the effect of foliar spray of Fe, Mn, Zn, or Cu applied as sulfate and B applied as borax on onion yield (Allium cepa L.) and its chemical components. Results showed that the highest dry yield was obtained by foliar application of ZnSO4 followed by the application of borax. Increment percentages were 9.7%, 2.2%, 23.6%, and 11.5% for the first growing season and 0.0%, 5.6%, 27.8%, and 18.5% for the second growing season over the control for Fe, Mn, Zn, and B treatments, respectively. On the other hand, copper treatment resulted in a slight, but not significant, yield decrease. Foliar spray treatments did not increase micronutrient concentrations except for spraying with ZnSO4, which increased Zn to its highest concentration and content. Significant correlation coefficients between P and Zn (-0.792*), Fe and Zn (+0.734*), Fe and Cu (-0.828*), Mn and Fe (-0.801*), and Mn and Cu (-0.809*) were recorded.