We acquired two 18F-deoxyglucose positron emisssion tomography (PET) scans on seven unmedicated pathological gamblers, at least 7 days apart. Following an injection of 5 mCi FDG, subjects carried out a computer blackjack task for 35 min under two different reward conditions: monetary reward and computer game points only. Relative FDG metabolic rate was obtained from regions of interest in the prefrontal cortex, cingulate, striatum and visual cortex. Monetary reward blackjack was associated with significantly higher relative metabolic rate in the primary visual cortex (Brodmann area 17), the cingulate gryus (Brodmann area 24), the putamen and prefrontal areas 47 and 10, compared to blackjack playing for points only. No area tested showed a significant decrease. This pattern suggests heightened limbic and sensory activation in the gambling for money condition with increased emotional valence and greater risk and reward, and confirms the salience of monetary reward in the development of pathological gambling.