Abstract: The growth and adaptation of tropical and subtropical herbaceous plants including sweet potatoes (Ipomoea batatas L.) are restricted by deleterious effects of low temperature stress or chilling injury. Chilling injury is the morphological and physiological damage sustained by plant tissue exposed to freezing temperatures. The aim of this investigation study was to evaluate the physiological functions of sweet potato genotypes to possibly explain tolerance to chilling injury. An experiment was conducted using four chilling tolerant sweet potato genotypes such as 105MS1, 108MS2, 180MS3, 183MS4 which were selected from seventy nine lines from three major variety crosses for tolerant to chilling injury. The effects of chilling exposure on chlorophyll fluorescence, peroxidase enzyme activity and other physiological parameters, such as specific leaf dry and fresh weight, percent leaf dry weight, percent leaf water content and stomata density were investigated. Following chilling treatment, qualitative visual ratings of the tolerant genotypes were different but the lowest score of the four on the scale of five was considered chilling tolerant. Chilling exposure decreased transpiration rate and stomata conductance but increased Electrolytic Leakage (EL) and Peroxidase Enzyme Activity (PEA). Genotypes differences were found in EL, PEA, chlorophyll fluorescence yield and other physiological functions following chilling exposure. Difference were also found among the genotypes in percent leaf dry weight and percent leaf water content which indicated the degree of water loss among the genotypes. The result suggest that breeding and selecting for chilling tolerance could enhance chilling tolerance in sweet potatoes.