A field experiment was conducted during 2008 at El-Sheikh Zuwayid Research station, North Sinai, Egypt. The main objective is to study the effect of intercropping patterns, water quantities and their combined effect on water use efficiency of kidney bean and corn crops. Statistically, this work designed as strip plot design with two variables (five intercropping patterns and three irrigation quantities) and three replicates. The obtained results can be summed up as follows: Increases for kidney bean and corn yields and their components, under intercropping system in the order of (1 bean: 1 corn) > (1 bean: 2 corn) > (2 bean: 1 corn) > (control (sole)). Likewise, both crop yields and their components with the amount of irrigation water in the order of (Q2 = ETc) > (Q1 = ETc × 0.8) > (Q3 = ETc × 1.2). The actual evapotranspiration of kidney bean and corn decreased either with intercropping systemin the order of (1 bean: 2 corn) < (2 bean: 1 corn) < (1 bean: 1 corn) < control (sole), or by decreasing irrigation water amounts. Statistical analysis shows significant differences among all treatments. Intercropping system (1 bean: 1 corn) with (Q1) and (1 bean: 2 corn) with (Q2) gave the best values of WUE. The investment ratios IR for both treatments gave 1.32 and 1.26 LE of kidney bean and corn, respectively. The study concludes the recommended treatments that could be practiced under North Sinai and similar conditions growing these crops together enable them to thrive and provide high-yield, high-quality crops with a minimum environmental impact.