Cadmium (Cd) is one of the heavy metals that it is produced from industrial, urban and agricultural activities which leads to environmental pollution. Accumulation of heavy metals in agricultural lands, soil pollution and finally transformation of these elements into crops in industrial areas is one of environmental problems which is hazardous for human health, animals and plants. In order to evaluate the effect of Cd on physiological parameters of safflower genotypes, an experiment was conducted under hydroponic condition at the College of Agriculture, Isfahan University of Technology, Isfahan-Iran, during June to October 2013. The experiment was arranged as a factorial based on a randomized complete block design with three replications. Six safflower ( Carthamus tinctorius L.) genotypes (Nebraska-10. Arak-2811, kouseh , S 149 , C 111 and K 12 ) were four levels of Cd including 0 (control), 1.5, 3 and 4.5 mgl -1 during the vegetative stage. Plant height, dry matter, leaf area, root dry weight, shoot dry weight, chlorophyll fluorescence (F 0, F m , F v /F m ), net photosynthetic rate (A), stomatal conductance to the CO 2 (g s ), substomatal CO 2 concentration (C i ), leaf chlorophyll a, b, and total chlorophyll and carotenoid contents, leaf proline content, lipid peroxidation (LP), membrane stability index and Cd concentration in shoot and root were measured. Leaf proline content of safflower genotypes was increased when Cd level at the solution increased, the highest increase (121.3%) was observed in 4.5 mgl -1 level of the Cd compared to the control. Leaf area, net photosynthetic rate (A), g s , leaf total chlorophyll content, leaf carotenoid content and quantum efficiency of PS II (F v /F m ) under 4.5 mg.l -1 level of Cd were decreased by 84.4, 50.5, 50, 31.8, 32.9 and 11.2%, respectively, compared to under control condition. Due to increase in Cd level lipid peroxidation of all genotype were increased. The greatest (77%) and smallest (60% and 61%) increases in lipid peroxidation under the 1.5 mgl -1 level of Cd compared to control were observed in Nebraska-10 and K 12 and C 111 , respectively. The smallest (44.7%) and greatest (62.1%) decreases in membrane stability index under the 4.5 mgl -1 level of Cd, compared to under control conditions were observed in C 111 and Arak-2811, respectively, suggesting is that the former genotype is more sensitive to the oxidative stress and hence indicates a higher level of electrolyte leakage. Cadmium concentrations of shoot and root under the 4.5 mgl -1 level of Cd were 52- and 156- fold of the control condition, respectively. Cadmium concentration at shoot for all genotypes was clearly lower than its concentration at root. Cadmium led to significant decreases in shoot biomass of all safflower genotypes. The latter decrease could be related to the decreases in photosynthetic surfaces, leaf chlorophyll and carotenoid concentration and PS II quantum efficiency. It was concluded that while Cd leads to considerable changes in growth and physiological attributes of safflower, some differences exist among genotypes. Keywords: Cadmium, safflower, proline, chlorophyll, lipid peroxidation, membrane stability index