The survival rate of alloxan-diabetic rats at 5 C was significantly less than that of control rats living at the same low environmental temperature. One-half of the diabetic animals died within the first 7 days of exposure while the remainder exhibited a marked susceptibility to cold injury in the form of tail gangrene. Shivering was decreased upon re-exposure to cold in both the diabetic and control rats following 20 and 45 days of cold acclimation. The diabetic animals had a tendency to shiver less than their controls. Diabetic rats also showed a significantly greater decrease in rectal temperature over a 90-min period at 5 C than did controls, in spite of a similar increase in oxygen consumption. This rectal temperature decrease was observed in both the diabetic and control groups before and after 20 days of cold acclimation. The data suggest that a problem of heat conservation exists in the diabetic rat, but tail-skin temperatures, as recorded, did not bear this out.