Smoking cessation increases caffeine blood levels, and this has been hypothesized to cause some of the symptoms of tobacco withdrawal (e.g., anxiety and insomnia). To test this hypothesis, 10 coffee drinkers who smoked cigarettes were entered into a completely within-subjects experimental design in which the effects of caffeine dose (0, 50, and 100 mg/coffee serving) and smoking status (smoking versus abstinence) were examined over a 4-day period. Self-reported and observed measures of tobacco withdrawal, caffeine withdrawal, and intoxication, as well as psychomotor tasks and vital signs, were completed daily; blood was drawn at the end of each period. Temporary abstinence produced typical withdrawal symptoms but did not significantly increase caffeine blood levels. Caffeine did not increase the severity of symptoms but did decrease the severity of withdrawal-induced hunger. These findings suggest that, in the absence of increased blood levels, caffeine does not increase the severity of tobacco withdrawal.