Methamphetamine is a highly addictive drug that has a neurotoxic effect on the brain. A growing body of evidence suggests that brain-derived neurotrophic factor (BDNF) is associated with addictive behavior. The present study investigated the changes in plasma BDNF concentration that were induced by chronic methamphetamine use. Using an enzyme-linked immunosorbent assay (ELISA), we measured peripheral BDNF levels in methamphetamine users and in a control group. The plasma BDNF concentrations of methamphetamine users were significantly higher compared with those of controls (2536.3 pg/ml versus 1352.6 pg/ml). This finding suggests that BDNF plays some role in the neurotoxicity of methamphetamine.