This study was carried out during the two successive seasons of 2015 and 2016 at the Experimental Orchard Faculty of Agriculture, Assiut University, Assiut, Egypt, to investigate the effect of cluster or berry thinning on fruiting of Ruby Seedless grapevines. Thinning treatments were performed after berry set.  The experiment was arranged in randomized set up as complete block with eight treatments and three replicates one vine per each. -   Fruit thinning by removing either 20 or 30% of cluster number/vine, as well as removing 30% of cluster shoulders considerably decreased the yield. Yield was unaffected carrying out by other thinning treatments compared to unthinned ones (control). -   Removing 20 or 30% of cluster number was responsive for increasing the cluster weight. Contrarly removed 30% of cluster shoulders materially deceased cluster weight, whereas cluster weight was unaffected by other thinning treatment compared to control. -   The best cluster compactness coefficient and form was obtained due berry thinning as removing 15% of its shoulders combined by 15% of cluster apical removal. -   All berry thinning improved the grapes quality in terms of increasing berry weight, berry coloration, total soluble solid and sugar contents and decreasing titratable acidity compared to control. From this study, it is clear that to get the high yield with good clusters and berry traits it is preferable for carrying out berry thinning by removing 15% of cluster shoulders along with cutting back 15% from the apical cluster or cutting back about 30% of the apical portion of the cluster.