Previous studies have consistently shown impairments of memory and learning in regular users of the neurotoxic drug ecstasy (3,4-methylenedioxymethamphetamine [MDMA]). In addition, deficits in working memory, planning ability and central executive control, as well as high cognitive impulsivity, were also reported in some studies. Hence, the memory decrements may be secondary due to other cognitive failures. The purpose of this study was to analyze the nature of the cognitive deficits of ecstasy users. Tests of memory, working memory, central executive function and cognitive impulsivity were administered to 60 currently abstinent ecstasy users and to 30 nonusers. Heavy ecstasy users (n=30, lifetime dose > or =80 ecstasy tablets) had lower memory performance than both nonusers and moderate users (n=30, lifetime dose <80 ecstasy tablets). In contrast, we found no group differences in central executive function, working memory, planning ability and cognitive impulsivity between ecstasy users and controls. Poorer memory and working memory performance was associated with a heavier pattern of ecstasy use. Low working memory, planning ability and central executive control and high cognitive impulsivity did not predict poor memory performance. Our results indicate primary memory dysfunction in heavy ecstasy users, which may be related to a particularly high vulnerability of the hippocampus to the neurotoxic effects of MDMA. Hippocampal dysfunction after ecstasy use may be a risk factor for earlier onset and/or more severe age-related memory decline in later years.