One of the most common nutritional deficiencies in vineyards is iron chlorosis due to high lime content and pH. In this study, physiological responses to iron deficiency stress were compared in nine grapevine genotypes. For this purpose, plants were grown in hydroponic culture having low iron [(-) Fe] or sufficient iron/control [(+) Fe] conditions. The [(-) Fe] plants were grown with 10(-6)M Fe EDTA for 40 days followed by 2x10(-7) M FeEDTA for 20 days. [(+) Fe] plants were grown with 10(-4) M Fe EDTA. To create iron stress, 10 mM NaHCO3 was added to the solution. In plants, active and total iron contents (mg/L), shoot active and total iron contents (mg/L), leaf chlorophyll status (SPAD), and root ferric chelate reductase enzyme activity were examined. All parameters were reduced in plants that were grown under iron deficient conditions. The highest active iron concentration in leaves was 108.27 mg/L in 1103 P grown in [(+) Fe] conditions. The chlorophyll content of leaves was 27.93 (1616 C) in [(+) Fe] conditions. The ferric chelate reductase enzyme activity of roots was higher in iron stress conditions. The highest level was 1395.78 in the 140 Ru genotype.