The present investigation was conducted during 2008 and 2009 seasons on common seedy guava trees grown in a private orchard at EL kefah village, Badr center Behera governorate to study the effects of different treatments of defoliation on tree yield and fruit quality at harvest time as well as loss in weight, decay and total loss during storage at room temperature as represent of marketing conditions of guava trees. All tested treatments gave significant increase in fruit quality(fruit weight, firmness, total sugars contents, vitamin c, acidity, SSC and SSC/ acid ratio), in both seasons of the study as compared with control. Both control fruits at the normal harvest period in the summer were held at 20-22 ^oCand RH 75% and fruits of other treatments were held at 12-14 ^oC and RH 82% at the winter season of harvest period in the winter. The obtained data indicated that urea 10% gave significant increase in yield of winter crop as compared with other treatments. In addition ZnSO₄ 2% + NH₄NO₃ 4% gave significant improvement in fruit quality as compared with other treatments. Concerning fruits held at room temperature, ZnSO₄ 2% + NH₄NO₃ 4% showed significant increase in in fruit quality (fruit weight, firmness, total sugars, vitamin c, acidity, SSC and SSC/ acid ratio) and gave the lowest weight loss after 9 days of room storage. Concerning control fruits (summer yield) the data indicated significant increase in yield, but a decrease in their quality and an increase in fruit weight loss and decay, due to fruits harvested in early dates in summer. The decay reached 100% after 3 days due to increased summer temperature. The winter crop of guava fruit trees from these treatments were good quality and its high price covered greatly the reduction in yield.