Two field experiments were carried out at Wady Elnatron, El-Behera Governorate, during 2007 and 2008 seasons, to study the effect of irrigation water amounts and nitrogen rates, on cucumber yield and the net return from these treatments, under drip irrigation system. Split-plot design was used with four replicates. The main plots were assigned by four irrigation water amounts (100%, 90%, 80% and 70%) of evapotranspiration (ETc). The sub-plots were randomly assigned by four nitrogen rates (0 addition (N₀), 50 (N₁), 100 (N₂) and 150 (N₃) kg N fed.^-1.) as ammonium nitrate. The other recommended agriculture practices were done. Four polynomial quadratic equations were established to show the following results: 1. The maximum and optimum N rates (X_m andX_opt ) were  increased as irrigation water amounts decreased in the two seasons. 2. The maximum and optimum cucumber yields (Y_m and Y_opt) were decreased as irrigation water amounts decreased in the two seasons. 3. The highest maximum yield (23.01 ton fed^-1), (1 feddan = 0.42 hectar),  the highest total value of yield (27605 L.E. fed^-1) and the highest return of N fertilizer (13864 L.E. fed^-1) were obtained as irrigation water amount 100% of ETc used in the two seasons. 4. The efficiencies of N rates (eX) were decreased as N  rates increased from N₀ to N₁, N₂ and N₃, respectively, with different irrigation water amounts . 5. The efficiency average (), the relative efficiency (EX) and the efficiency of nitrogen fertilizer at optimum rate (eX_opt), were decreased as irrigation water amounts decreased. 6. The soil nitrogen content during plant growth (X_s) was increased as irrigation water amounts decreased. 7. The contribution of soil N was decreased as irrigation water amounts decreased in the two seasons. 8. The contribution of N fertilizer was increased as N levels increased in the two seasons.