This investigation was carried out during the seasons of 2006 and 2007 to study the effect of some dormancy - breaking chemicals on bud constituents, bud break, flower fire blight infections, fruit set and yield of "Le Conte" pear trees. The data revealed that, spraying Le-Conte pear trees at 1^st February with Dormex at 1% + mineral oil at 3% was effective for hastening the date of bud burst, enhanced the bud burst percentage and gave pronounced effect on bud constituents, flower fire blight infections, fruit set and yield. Furthermore, spraying Le-Conte pear trees with mixture of Dormex at 1% and mineral oil at 3% is an economic treatment than the use of hydrogen cyanamide alone at 4% as recommended which is rather expensive under the Egyptian conditions.