Water and fat contents of wild and captive Sorex araneus, S. minutus and Neomys fodiens were determined. The influence of sex, locality, body weight and age on water and fat contents of wild shrews are discussed. A seasonal cycle in both water and fat content of wild shrews is demonstrated. An investigation of captive shrews revealed fat contents to be considerably greater than in wild shrews. It is concluded that the seasonal differences in water and fat contents found in this study are of insufficient magnitude to account for the loss in body weight of wild shrews in winter or to be of any great survival value to them.