Methamphetamine (METH) abuse has become increasingly popular among young people. This stimulant drug has neurotoxic effects that can alter behavior. The present study investigates its effects in a behavioral paradigm. Selectively bred Occidental High- (HiS) and Low- Saccharin (LoS) rats were trained to bar-press for food on a schedule that allows changes in external (incentive) versus internal (regulatory) motivation to be distinguished.They then each received four treatments: METH/Saccharin pellets; METH/Regular pellets; Saline/Saccharin pellets; and Saline/Regular pellets. Treatment days alternated with recovery days. Preliminary results suggest that METH enhanced feeding regulation among LoS rats and reduced it among HiS rats. The LoS rats also were more sensitive to pellet flavor. These alterations indicate that METH affects the basic reward system, with different individuals affected differently. Implications for human behavior warrant further exploration.