This study was carried out during 2007 and 2008 seasons to study the effect of potassium and magnesium as soil fertilization under bud load of 40 or 60 eye/vine on bud behavior, yield and berry quality of Flame Seedless grapevines. Potassium was applied as potassium sulphate at two rates 150 and 300 g/vine and magnesium was applied as magnesium sulphate at 30 and 60 g/vine.                 Obtained data reveal that, both potassium and magnesium fertilization under 40 or 60 eye/vine increased bud burst and fertility percentages than the control. Furthermore, potassium fertilization at 300 g with 30 g magnesium sulphate per vine under leaving 40 eye/vine gave the highest bud burst percentage than those obtained under leaving 60 eye/vine. Also, potassium fertilization at 300 g with magnesium sulphate at 60 g/vine under leaving 60 eye/vine gave higher number of clusters and yield/vine than those obtained under leaving 40 eye/vine. Yet, potassium fertilization at 300 g with 30 g magnesium sulphate per vine under leaving 40 eye/vine gave higher cluster and berry weight, SSC, SSC/acid ratio and anthocyanin content than the other levels of potassium or magnesium fertilization under leaving 60 eye/vine.