The recreational drug 'ecstasy'[3,4-methylenedioxymethamphetamine (MDMA)] exerts a potent action on central serotonergic and dopaminergic neurons. These neurons utilize neurotrophins for their survival and function. In order to explore MDMA effects on neurotrophins, we measured by enzyme-linked immunosorbent assay the serum levels of brain-derived neurotrophic factor (BDNF) and nerve growth factor (NGF) in 'ecstasy-addicted', 'ecstasy-addicted with signs of psychosis' and 'healthy' subjects. We found that BDNF serum levels were significantly increased in both groups of 'ecstasy-addicted' as compared with 'healthy subjects', supporting the hypothesis that BDNF is involved in MDMA action.