['Psychomotor stimulants previously have been found to increase the frequency of cigarette smoking, but it is unclear whether this is due to a non-specific increase in general activity or a specific increase in the reinforcing effects of smoking.', 'To investigate whether d-amphetamine increases the relative reinforcing effects of cigarette smoking.', 'Ninety minutes after d-amphetamine (7.5, 15 mg/70 kg) or placebo administration, 13 male and female subjects participated in 3-h sessions during which they could make a maximum of 20 choices between cigarette smoking (two puffs per choice), earning money ($0.25 per choice), or neither. In separate sessions, using the same subjects, the effects of d-amphetamine on the frequency of ad libitum smoking was assessed.', 'During choice sessions, d-amphetamine dose-dependently increased smoking choices from 4.2 +/- 0.6 to 5.7 +/- 0.6. During sessions in which subjects smoked ad libitum, d-amphetamine increased number of cigarettes smoked from 2.8 +/- 0.4 to 3.8 +/- 0.6. Breath carbon monoxide (CO) levels, a measure of smoke exposure, showed corresponding dose-related increases.'] Does d-amphetamine increase choice of cigarette smoking over monetary reinforcement?