This analysis and critique was written in response to the critique of ecstasy research written by Cole et al (2002). While acknowledging the methodological flaws present in most studies of ecstasy users, Croft believes that the existence of these flaws does not warrant strong skepticism concerning findings from studies of ecstasy users. The author argues that uncertainty concerning strength of illicit ecstasy tablets would tend to reduce rather than increase likelihood of finding associations between ecstasy use and changes in cognition or mental health. If this is so, then studies that do find associations between ecstasy use and long-term deleterious effects should be considered as presenting conservative estimates of the effects of ecstasy use. Croft considers findings from non-human animal studies and findings of transient depression in ecstasy users as supporting hypothesized serotonergic neurotoxicity in humans. Some of the researcher's own study findings indicate that cannabis use, and not ecstasy use, might be more closely associated with some neurocognitive differences, but findings from an evoked potential study are given as evidence of reduced serotonergic function. Despite evidence from a number of recent publications indicating that psychological problems may also be at least partly due to use of other drugs, Croft sites studies finding a link between ecstasy use and psychological problems as evidence of neurotoxicity. Overall, the author believes that convergent evidence from human and non-human studies are strong enough to support the presence of long-term neurotoxic effects after ecstasy use.