Sunflower (Helianthus annuus L.) is a potential cash crop for the southeasternUnited States for production of cooking oil or biodiesel. Two years (2006 and 2007) of experiments were conducted at each of five locations in Mississippi to evaluate the effect of planting date (April 20, May 20, and June 20), and hybrid (DKF3875,DKF2990,DKF3510,DKF3901, PR63M80, PR62A91, PR63A21, PR63M91, andPR64H41)on seed yield, oil content, andoil composition of sunflower. Seedoil concentration varied from25 to 47%. The oleic acid concentration in the oil was greater than 85% for DKF3510 and PR64H41, above 65% for PR63M80 and PR63M91, and intermediate for the other hybrids. Total saturated fatty acids (TSFA) concentration in the oil (the sum of palmitic, stearic, arachidic, behenic, and lignoceric acids) ranged from 6.3 to 13.0%, with DKF3510, PR63M91, and PR64H41 having lower concentration of TSFA than the other hybrids.Mean seed yields ranged from 997 to 2096kgha−1 depending on location. Mean oil yields at the five locations ranged from 380 to 687kgha−1, and calculated biodiesel production ranged from 304 to 550kgha−1. Seed and oil yields in this study suggest sunflower in Mississippi should be planted by the last week of May. Later planting (20 June) may significantly decrease both seed and oil yields in the non-irrigated system in Mississippi and in other areas of the southeastern United States with similar environmental conditions. © 2010 Elsevier B.V. All rights reserved.