The effects of immunosympathectomy and acclimation to cold on the incorporation of glucose-U-14C into lipids of the interscapular brown adipose tissue, epididymal fat pad, and liver of rats have been investigated. Acclimation to cold was associated with an increase in glucose recovered in the total lipids of brown adipose tissue. These changes in glucose recovery were the same in immunosympathectomized as in intact rats. The brown adipose tissue of the two groups of cold-acclimated rats differed, however, in that this tissue in the immunosympathectomized animals was larger and had more lipid. Suggestions are raised to explain these findings. Neither immunosympathectomy nor cold acclimation produced any changes in white adipose tissue. Immunosympathectomy did not alter the liver's handling of glucose. However, cold-acclimation was associated with an increase in the relative weight of the liver and a decrease in glucose recovery in liver lipids.