Mint can be grown in the most parts of Iran but cold and very cold areas are not suitable for the cultivation of this plant. The desired temperature for growth is 10 ° C .So one of the factors limiting the plant growth in cold climates is low resistance to low temperatures.Two experiments were conducted inthe field (control) and greenhouse (incubator). Greenhouse experiment was performed in a completely randomized designwith three replications.In the stage, 8 mint genotype including Tabas, Qazvin, Isfahan and Kermanshah from Mentha pipertia L ., Isfahan and Hamedan from Mentha longifolia L . and Loresta and ahvazfrom Mentha icata L . were evaluated at five temperatures of -10, -5, 0 , 5 , 10 ° C inside incubator. In the field experiment, eight genotypeswere planted in a randomized complete block design with three replications andwere evaluated under field temperature . In incubator , electrolyte leakage, chlorophyll fluorescence, leaf damage, leaf area and proline content (on the resistant and sensitive genotypes) were measured.In field experiment, electrolyte leakage, chlorophyll fluorescence,leaf area, essential oil percentage and spring growth were measured. The results in controlled conditions (electrolyte leakage,chlorophyll fluorescence and symptoms of chilling injury) showed that temperatures above zero (10, 5, and zero), have not significantly affected the genotype and damages have caused under freezing temperatures (frost). Assessment of chlorophyll fluorescence in controlled conditions (incubator) showed that none of the eight genotypes of mint were affected at temperatures above zero (10, 5, and zero) and the maximum and minimum of injury happened at -5 and -10 (frost) were belong to lorestan and hamedan, respectively. Comparing genotypes of mint regarding chlorophyll fluorescence and electrolyte leakage showed similarity in the results so thatahvazand Isfahan were the most resistant and sensitive genotype, respectively, based on fluorescence in both conditions and tabaswas the most resistant genotype based on electrolyte leakage. In terms of electrolyte leakage under controlled conditions (incubator), the maximum leakage in freezing temperatures of -5 and -10 was observed in ahvaz. The genotypes of lorestan and ahvazhad the maximum leaf areaand chlorophylle florescence in the field and control condition at 10 ° C . The genotypes of isfahanand tabas from M. piperita had the highest and lowest content of essential oil, respectively, after cold period. The same genotypes had the most and the least spring growth, respectively. When temperature decreased, the amount of proline in genotypes of pipertia species (Tabas, Qazvin, Kermanshah and Isfahan) increased. Besides, comparing these genotypesshowed that the genotype Isfahan had the minimum content of proline in response to stress conditions. Keywords: Cold stress, freezing stress, mint germplasm, resistance