The present investigation was conducted during 2007 and 2008 seasons to study the effect of compost tea on vegetative growth, fruiting and yield, leaf mineral content and fruit quality of Washington navel orange trees. All tested treatments gave generally significant increase on shoot length, leaves number/shoot and leaf surface area in both seasons of the study as compared with control, while T6 ( 20L compost tea at five equal doses in mid  each February, March, April, June and August) gave the highest significant increase of shoot length, leaf number/shoot and relatively leaf surface area (14.02-14.25 cm) (7.22-7.72 leaf) (18.74-17.54cm²) in 2007 and 2008 seasons, respectively. In addition, T6 treatment relatively gave significant increase in fruits number and yield /tree (397.81-225.25 fruit and 94.84-55.10 Kg/tree, in both seasons, respectively. Moreover T6 gave significant increase in leaf content of nitrogen, phosphorus and potassium in both seasons of  the study compared with control (2.99-3.08%, 0.276-0.288% and 1.98-2.02% in 2007 and 2008 seasons, respectively. Concerning to nitrate and nitrite concentration in the fruit juice, T6 resulted in the lowest values of both compounds (4.42-4.64and 0.087-0.091 ppm/100ml) in 2007 and 2008 seasons, respectively).