High soil salinity occurs in a large area where sunflower (Helianthus annuus L.) is produced in the USA and limits production capabilities there and in many parts of the world where sunflower is grown, particularly under irrigated conditions in arid climates. A wild species of sunflower, Helianthus paradontsHeiser, was noted to be unusually tolerant to saline conditions. This investigation examined the salinity tolerance of five interspecific germplasm lines derived from crosses of. H. paradorus with cultivated H. annuus and studied the inheritance of salinity tolerance. Preliminary results indicated that three interspecific crosses had tolerance to a 15 (EC. 24.7 dsm-') g/l NaCl solution in both a seedling and germination test. These germplasm lines and a susceptible inbred line were crossed. Segregation ratios of Fz and backcross generations indicâted that one major dominant gene, proposed as Sar, controlled seedling tolerance to salinity. A recessive modifier gene also appeared to be affecting seedling tolerance to salinity. In the germination study, no single gene was clearly identified for control of tolerance to salinity; however, a level of tolerance was found and appeared to be dominantly controlled. These seedling and germination procedures will be further tested to determine their utility in breeding programs desiring increased tolerance to soil salinity.