The effect of fruit thinning rate on regulate bearing, yield and fruit quality of Balady mandarin trees was investigated during two successive seasons, 2006 and 2007.  Fruit thinning were performed when the fruit diameter reached about 25-30 mm, as hand thinning by removing 20, 30, 40 or 50% of fruits number per tree.  The experimental treatments were arranged in a complete randomized block design.  The results of this investigation could be summarized as follow: -                      Fruit thinning caused a significantly decreased in fruits number and yield/tree and relative yield during first season (on-year).  Whereas, during the second year (off-year), all fruit thinning significantly increased the produ-ctivity of trees compared to unthinned ones. -                      Removing 40% of fruits number/tree was the most effective thinning treatment in increasing and regulating the tree produ-ctivity. -                      The fruit weight and dimension were significantly increased as a result of fruit thinning in either (on-year) or as average of two studied seasons. -                      Such fruit traits were significantly decreased in (off-year) seasons compared to unthinning ones. -                      All fruit thinning rates significantly increased fruit juice content of soluble solids, sugars and V.C and decreased total acidity. -                      Fruit thinning as removing either 40 or 50% of fruits number/ tree gained the highest score record, 99.8 and 93.7 units, respectively as a general evalua-tion of treatments. On the account of the present findings, it can be concluded that manual hand fruit thinning at 40% when the fruit diameter is about 25-30 mm was the best economic treatment for Balady mandarin trees to obtain the high yield with good fruit quality, furthermore, overcome the alternate bearing which the major problem for such cultivar