In winter cultivation of leaf crops, cold-shock often leads to severe wilting as well as freezing injury. Although wilting at low temperature is commonly observed in many plant species, the mechanism of the response is still unclear. Brassica campestris L. (cv. Komatsuna) is a good test crop for understanding the process of wilting and recovery due to its ability to acclimate to cold conditions. We investigated variations in the stomatal conductance and leaf water potential in response to low temperature. The results suggest that wilting was primarily caused by reduced water-uptake, and the stomatal response to water stress was not affected by lowered temperature. Osmotic potential of cold acclimated plants that had recovered from wilting was lower by 0.6 MPa than in less acclimated plants. The depression in osmotic potential was accounted for an increase in sugars. Sugars are thought to function mainly as cryo-protectants. However, our results suggest that accumulation of these solutes is important not only for freezing tolerance but also for prevention of cell dehydration under low temperatures.