When cigarette smokers with chronic lung disease become acutely ill or require surgery, they are often forced to stop smoking and may use nicotine gum. Smoking is known to accelerate the metabolism of theophylline, but the effects of short-term abstinence or nicotine gum on theophylline metabolism have not been reported. We studied the effects of brief tobacco abstinence and nicotine gum on theophylline elimination in healthy volunteers. Abstinence from smoking for 1 week resulted in a 37.6% decrease in clearance and a 35.8% increase in half-life. Nicotine gum had no effect on theophylline clearance. Our data indicate that at least partial normalization of the enzyme-inducing effects of smoking can be seen after brief cigarette abstinence. For smokers who are taking theophylline chronically, their dose of theophylline will need to be reduced by one fourth to one third after brief tobacco abstinence. Plasma concentration monitoring may be necessary for optimal dosing of theophylline in such patients.