The seedlings of 3 green bean genotypes ('Balkiz', Ferasetsiz', 'Local Genotype') were grown for 4 weeks at 30/15 degrees C (day/night) temperature with 65% humidity and then transferred to a growth chamber. The temperature in the growth chamber was increased stepwise to 35, 40, 45 and 50 degrees C to create a heat-stressed environment. In addition, to determine HST (LT50) the leaf discs of each genotype were exposed to 35, 40, 45, 50, 55 and 60 degrees C. According to results, Ferasetsiz and 'Local Genotype' hod the highest leaf relative water content (RWC), while the 'Balkiz' hod the lowest. However, Ferasetsiz' and 'Local Genotype' had the lowest loss of turgidity and malondialdehyde (MDA), while 'Balkiz' had the highest. The leaf area and chlorophyll content (Chl) were not associated with the HST of genotypes. Many protein hands, in mass range 27-157 kDa, were detected depending on the genotypes and heat treatments. Besides, a few new proteins' appeared in response to heat stress. Based on the data collected, 'Ferasetsiz' and 'Local Genotype' were determined to heat tolerant genotypes, while 'Balkiz was relatively' heat sensitive genotype.