Varenicline (Chantix) is a novel smoking-cessation agent that acts at a number of nicotinic acetylcholine receptors. The aim of this study was to determine the behavioral effects of acute varenicline administration in human subjects. The effects of doses of varenicline (0.5, 1 and 2 mg), methylphenidate (40 mg; positive control) and placebo were assessed in 8 (7 males, 1 female) cigarette smokers. Staggered, double blind dosing was used to examine eating and smoking behavior during the peak effects of varenicline and methylphenidate. Starting at the published time to peak plasma levels of these drugs, subjects were allowed to smoke and eat ad libitum for 4 h. Acute varenicline was devoid of behavioral effects. Methylphenidate produced prototypical stimulant-like effects (e.g., increased smoking behavior; decreased caloric intake). The present results indicate that acute varenicline administration does not alter smoking behavior although the low number of subjects limits the ability to detect small effects. Future research should examine the effects of chronic varenicline on smoking and eating behavior in humans, particularly using operant techniques to determine whether varenicline alters the reinforcing effects of cigarettes and food in humans.