A field experiment was carried out during the two successive growing seasons 2009/2010 and 2010/2011at a private orchard located at, Motobus, Kafr El Sheikh Governorate, Egypt, on twenty years old Navel orange (Citrus sinensis, Osbeck) to study the impact of irrigation treatments on Navel orange yield, quality and some water relations in the North Nile Delta region. They were budded on Sour orange (Citrus aurantium L.) rootstock spaced at 5 x 5 metre apart. The orchard soil is clayey. The trees were selected in a good health condition and uniform in both vegetative growth and fruit load. The experimental design used in this present study is a randomized complete block design with five replicates. Fifteen trees were selected in this study and divided randomly into three groups; each group was subjected to one of the following irrigation treatments: I₀ (Traditional irrigation, (control) treatment like local farmers practiced in the studied area (16 irrigations through the whole growing season), I₁ (giving 12 irrigations through the whole growing season) and I₂ (giving 8 irrigations through the whole growing season, which represents stressed conditions on plants).      The highest values fruit set%: fruit weight (g) and yield as kg/tree for the two studied parameters were recorded under irrigation treatment I₂ comparing with the other irrigation treatments I₀ and I₁.   Obtained data in the two growing seasons showed that the highest values                    for irrigation water applied were recorded under irrigation I₀ comparing with other irrigation treatments I₁ and I₂ in the two growing seasons and the values are 7500, 5250 and 4150 m³/fed. For water applied as the mean values of first and second growing seasons, respectively. On the contrary, the lowest values for water applied were recorded under irrigation treatment I₂ in the two growing seasons.  The highest values PIW (Productivity of irrigation water (kg m^-3)) and PW (water productivity (kg m^-3)) for the two studied parameters were recorded under irrigation treatment I₂ comparing with the other irrigation treatments I₀ and I₁. Generally, the values of the two studied parameters can be descended in order I₂> I₁> I₀.