The present study was carried out at Sakha Agricultural Research Station, Kafr El-Sheikh, Governorate during the two successive seasons 2006 and 2007 to investigate the effect of three irrigation intervals i.e. one, two and three weeks on the productivity and some water relations of sunflower. A slit plot design with three replicates was used. The main plots were assigned to the irrigation intervals, while the sub-plot were devoted to irrigation levels i.e. irrigation till field capacity plus 10%. In addition, three other levels based on Ibrahim, Hargareves and FAO Peman-Monteith equations. Results could be summarized as follows:                 Irrigation every 7 days significantly increased stem and head diameter, the weight of 100 seed, oil content and seed yield. Irrigation according to Ibrahim equation was superior in stem and head diameter, oil content and seed yield. Irrigation every one week according to Ibrahim equation was resulted in the highest seed yield of s1348.53 kg/fed. (mean of 2 season).