Nicotine given subcutaneously to rats raised the levels of plasma free fatty acids (FFA) and blood glucose, the content of FFA and glycerol in adipose tissue also being increased. The basal lipolysis of adipose tissue obtained from nicotine-treated rats was increased, while the lipolytic effects of norepinephrine or theophylline remained unchanged or were slightly diminished. The rise in plasma FFA was inhibited by the administration of 5-carboxy-3-methylpyrazole, an antilipolytic agent, or of a β-adrenergic blocker. Nicotine failed to raise plasma FFA in previously adrenalectomized rats. However, this effect was restored by the administration of corticosterone. No elevation of lipid content in the liver and heart was observed after single or repeated treatment.