In order to study the effect of two planting distances and four irrigation regimes on growth traits, seed yield and water use efficiency of sunflower (Helianthus annus L.) plants, two filed experiments were conducted during 2020 and 2021 summer seasons in a loamy sand soil at Abu Hammad District, Sharqia Governorate, Egypt. Split plot design in a randomized complete block design in three replicates was used. The two planting distances between hills (20 and 30 cm) were assigned to the main plots, sub-plots were devoted to four irrigation regimes (Irrigation at 50% available water "AW"; 75%, 50% and 25% of the 50% AW). Results stated that irigating at 50% and 75% of AW were at par of in each of leaf area index, plant height, stem diameter, seed yield, head diameter, and number of seeds/head, in both seasons. Hence, saving about 21.97% (358.88 m³/faddan) of the full water needed for irrigation. Planting density based on planting distances where increasing plant density from 20000 to 30000 plant/faddan (4200 m²) through narrowing planting distances form 30 cm to 20 cm improved each of plant height, leaf area index, and seed yield as well as raising water use efficiency.