The citrus brown mite, Eutetranyohus oriental& (Klein) (Family: Tetranychidae) is considered one of the important mite pest attacking citrus trees causing serious damage to leaves and fruits especially during the last three seasons (2000-2003). To enhance the exportation of citrus fruits and reduce the applications numbers of pesticides. We concern in this study to use phytoseiid mite, Neoseiulus californicus as biocontrol agent for controlling this dangerous mite pest on citrus trees. The predatory mite was reared on the two-spotted mite, Tetranychus urtkae Koch and released at three levels 40, 50 and 70 individuals per tree at average level infestation 4.64, 5.06, and 4.70 mite per leaf, respectively, while it was in un release tree 4.69 individuals/leaf. After releasing the predator mite the mite pest, E. orientalis population generally declined gradually and percentage reduction in the population of mite pest after four months of releasing reached 57.84, 73.76 and 88.25%, respectively. Conclusion: The above mentioned results indicated the possibility of controlling the citrus brown mite, E. orientakson citrus trees by releasing the predatory mite, N. califomicvs with the rate of 70 predators per tree without any damage on leaves, resulting good production free of acaricide reduces.