Abstract: Low temperature damage is a common problem for early-planted soybean, because it is a tropical plant and is sensitive to low temperatures. In this research plant`s response to cold acclimation and nonacclimation was investigated in soybean (Glycine max). Seedlings were exposed to 15�C (cold-acclimated) or 25�C (nonacclimated) for 24 h, under 250 �mol m 2 s 1 Photosyntetically Active Radiation (PAR). Then, all plants were exposed to chilling temperature at 4�C for 24 h and allowed to recover at 25�C for 24 h. Physiological responses to chilling, including, MDA, proline, chlorophyll a and b and carotenoids and total protein contents were measured in soybean to identify mechanisms of chilling tolerance. Relative water content showed that cold-acclimated plants were less affected by chilling compared to nonacclimated plants. Cold-acclimated plants also recovered faster from chilling injury than nonacclimated plants.