The experiment was conducted at Horticultural Orchard, Assiut University during two successive seasons of 2004/2005 and 2005/2006 on 6 years old of Red Roomy grapevines. The study aimed to investigate the effect of defoliation alone or combines with HC or thiourea on bud burst, yield and fruit quality of Red Roomy grape cultivar. The defoliation treatments were manually executed on four successive dates, November 1^st, November 15^th, December 1^st and December 15^th each season by removing all the vine leaves on each date. The pruning was done after each defoliation date then the spraying solution was added. The dormancy breaking agents used were hydrogen cyanamide at 1.47 % (Dormex at 3 %) and thiourea at 2%. The present study revealed that defoliation enhanced bud break, yield and fruit quality. The effectiveness was increased when it combined with HC or Thiourea