The present study was designed to test the effects of nicotine and nicotine withdrawal on weight change and food consumption in rats. Twelve male and 12 female three month old Sprague-Dawley rats were divided into three treatment groups: 0.2, 0.4, and 0.6 mg nicotine/kg body wt. Half were given subcutaneous nicotine treatment for three weeks and then saline for three weeks; treatment sequence was reversed for the other half. Injections were administered three times daily throughout the experimental period. Prior to treatment, baseline measures were established for both food consumption and weight. Mean differences in weight change were calculated on a weekly basis throughout the experiment. Overall tests indicated that nicotine withdrawal produced significant (p less than 0.05) weight gains and nicotine administration produced inhibition of weight gain. A significant sex X drug X time interaction (p less than 0.05) demonstrated that food consumption increased when nicotine was discontinued and decreased when nicotine was administered. Specific comparison tests showed these effects on food consumption and weight were strongest at the 0.6 level and that larger effects were obtained for males than for females.