Technical Abstract: Sunflower (Helianthus annuus L.) is becoming an increasingly important source of edible vegetable oil throughout the world because of its high polyunsaturated fatty acid content and low cholesterol. The increasing demand for this oil will undoubtedly promote increased acreage of sunflower in the western USA, where some soils are or have the potential to become saline. Since there is a lack of information about the response of sunflower grown under saline conditions, a 2-yr field plot study was conducted. Six salinity treatments were imposed on a Holtville silty clay (clayey over loamy, montmorillonitic [calcareous], hyperthermic Typic Torrifluvent) by irrigating with Colorado River water artificially salinized with NaCl and CaCl2 (1:1 by weight). Electrical conductivities of the irrigation waters both years were 1.4, 2.0, 3.0, 4.0, 6.0, and 8.0 dS/m. Seed yield and oil content of the seed were measured. Relative seed yield of four hybrids, Sigco 452, Sigco 465A, Sigco 849, and Sigco 954 was unaffected by soil salinity up to 4.8 dS/m (electrical conductivity of the saturation extract; ECe). Each unit increase in salinity above 4.8 dS/m reduced yield by 5.0%. These results indicate that sunflower would be classified as moderately tolerant to salinity. Yield reduction was attributed primarily to a reduction in seeds per head. Oil concentration in the seed was relatively unaffected by increased soil salinity up to 10.2 dS/m.