This research was conducted to determine the most responsive phenological stage for supplementary irrigation of the durum wheat in a primary stationary region. It consisted of six different water treatments in addition to control (non irrigated) : 1-From planting to seedling emergence; 2-From planting to tillering; 3-From planting to booting; 4-From planting to flowering; 5-From planting to the end of the milk stage; 6–Sowing irrigation and irrigation according to necessity throughout the milk stage. The study has been repeated in four blocks for three seasons from 2002 to 2005. The results of the first two seasons showed that the: The treatment from planting to booting, was canceled because of the rain and soil dampness during this growth period. A significant increase in production, water use efficiency, and one 1000 kernel weight, of both 5th and 6th treatments was noticed in comparison with other treatments and the control. Results of the three seasons were varied due to the environmental variation in temperature and amount of rainfall.