Chronic use of MDMA (3,4-methylenedioxymethamphetamine), or Ecstasy, is believed to lead to impaired psychological performance, including well-documented decrements in laboratory and field tests of retrospective memory. Less is known about the impact of Ecstasy on aspects of 'everyday' memory, despite obvious concerns about such effects. The three studies reported here focused on the impact of chronic Ecstasy use on prospective memory (PM), associated central executive function and other aspects of day-to-day cognition. In study 1 46 regular Ecstasy users were compared with 46 Ecstasy-free controls using the Prospective Memory Questionnaire (PMQ). Ecstasy users reported significantly more errors in PM (remembering to do something in the future); these findings persisted after controlling for other drug use and the number of strategies used to aid memory. No difference was found between representative subgroups on the Lies Scale of the Eysenck Personality Questionnaire. In study 2 a different group of 30 regular Ecstasy users and 37 Ecstasy-free controls was assessed on the PMQ and on a central executive task comprising verbal fluency measures. The results confirmed the significant impairments in long- and short-term PM and revealed corresponding impairments in verbal fluency. In study 3 15 Ecstasy users, 15 cannabis users and 15 non-drug users were assessed using the Cognitive Failures Questionnaire, which requires participants to provide ratings of the frequency of various day-to-day cognitive slips. The results indicate that the Ecstasy users did not perceive their general cognitive performance to be worse than that of controls. Taken together, these results suggest that Ecstasy users have impaired PM that cannot be explained by an increased propensity to exaggerate cognitive failures. These may be attributable, in part, to central executive deficits that are due to frontal lobe damage associated with Ecstasy use. Copyright 2001 John Wiley & Sons, Ltd.