Safflower is a medicinal crop which is commercially cultivated for vegetable oil extracted from the seeds.Drought stress basically decreases safflower oil and seed yield,especially in sensitive phenological stages. Todecreasethese drought stress negative effects, atrazine foliage sprayingin low concentration would be useful as an anti-transpirant. The current study was carried out to clarify possibility of oil and seed yield enhancement of safflower (cv. Sina) by foliar atrazine application in three phenological stages including stemming, flowering and seed filling at 0, 80, 120 and 160 g a.i./ha concentrations in a rainfed safflower farm in Miyaneh region, Iran. The experiment was performed in factorial based on randomized complete block design with three replications. Applying atrazine at 80 and 120 g a.i./ha specially in flowering stageincreased significantly oil content from almost 30 to more than 35%. It also increased photosynthesis rate and seed and oil yield. There was no effect on oil content when atrazine was applied in stemming stage. Foliar application of atrazine in 120 g a.i./ha could be recommendable in rainfed safflower production, but the higher dose up to 160 g a.i./ha would be toxic and misplaceablative effect on safflower seed and oil yield.