Sunflower (Helianthus annuus L.) suffers from terminal drought accompanying with high temperature stress since it grows mainly in rain fed areas. Therefore, plant breeders try to improve more drought tolerant varieties and to screen their genetic materials for drought resistance. The present study was conducted to determine drought tolerance levels of sunflower male inbred lines developed by Trakya Agricultural Research Institute (TART), Edirne, Turkey. Inbred lines grown under controlled environmental conditions were sorted by polyphasic chlorophyll a fluorescence measurements. Drought stress applications were performed at three sunflower growth stages as R-3 (vegetative), R5-1 (head formation) and R-6 (milky seed). Based on applied different JIP-Test (analysis of O-J-I-P fluorescence transient) parameters such as Drought Factor index (-DFI) and Damage index (-DI), 70352 R, 8129 R, 0536 R and 9947 R restorer lines were found more drought tolerant than those of the other examined sunflower inbred lines, whereas TT 317 R and TT 199 R were determined as more drought sensitive than others. The drought tolerant inbred lines will be helpful to improve drought resistance in sunflower breeding programs.