Common beans ( Phaseolus vulgaris L.) are of the most crucial nutritional plants rich of protein and are the most important legumes in the world and and also in Iran. On the other hand, drought stress is themajorlimiting factorforcrop productivity and achieving maximum yield potential. However, the atmospheric CO 2 concentratiowill reach 700-800 µmol mol -1 by the end of the 21st century, according to the IPCC. Accordingly, an open-top chamber experiment was conducted at Isfahan University of Technology, Iran, to evaluate the growth and some physiological characteristics of common bean genotypes under different atmospheric CO 2 concentration and irrigation water levels. Fifteen common bean genotypes (cheetah, red and white common beans) were grown under two irrigation regimes (based on 40 and 65% soil-water depletion as control and water deficit treatments, respectively) as a factorial experiment in a randomized complete block design with three replications at two atmospheric CO 2 conditions (400 ± 50 and 700 ± 50 ?mol mol -1 ). The results showed that with increasing CO 2 , the average shoot dry weights of common bean cultivars were enhanced by 82 and 44% under the control and water-limited conditions, respectively. The highest and the lowest increases of shoot dry weights under control irrigation belonged to Cos16 and Pak cultivars (173 and 21%) and under water-limited irrigation belonged to Sadri and Akhtar cultivars (145 and 16%), respectively. Under ambient CO 2 , water deficit reduced root dry weights of bean cultivars excluding Cos16, Ofogh, Almas, Dorsa, Saleh and Sadri. The highest and the lowest decreases were observed in Derakhshan (45%) and Shekoofa (20%) cultivars, respectively. However, under elevated CO 2 , root dry weight was also reduced in by water deficit stress but not in bean cultivars of Akhtar, Daneshkadeh, Dorsa, Shekoofa, Sadri and Ghaffar cultivars. The highest and lowest decreases were observed in Almas (56%) and Goli (28%) cultivars, respectively. Water deficit decreased chlorophyll a concentration of Cos16 and Sadri cultivars under both ambient and elevated CO 2 , while no significant effects of water deficit was observed on Derakhshan and Yaghoot cultivars. Increased CO 2 under control irrigation decreased the enzyme activity of catalase in Cos16, Derakhshan and Sadri cultivars but increased catalase activity in Yaghoot. While under water-limited condition, increasing CO 2 reduced the catalase activity in Sadri and Yaghoot but not those of the other two cultivars. Elevated CO 2 increased the water stress susceptibility index (SSI) of Cos16, Ofogh, Koosha, Goli and Yaghoot cultivars but decreased SSI related to Almas, Shekoofa, Sadri and Ghaffar cultivars. However, SSI values of the other cultivars were not affected by elevated CO 2. In general, it can be stated that there was considerable genetic variation among common bean cultivars in response to elevated CO 2 under both control and water-limited conditions. In addition, the effect of elevating CO 2 on dry matter accumulation and physiological characteristics of bean plants depended on soil moisture and cultivar. Also, under the influence of CO 2 concentration, reducing or increasing sensitivity to water stress was cultivar dependent. The results of the present study may be useful in improving crop production management as well as in developing new breeding strategies for introducing common bean genotypes in the face of climate change. Keywords: Antioxidant enzyme activity, Bean, Carbon dioxide, Genetic diversity, Stress susceptibility index