The use of amphetamine type stimulants, particularly MDMA, is a global concern. Little research has been conducted on the association between MDMA use and everyday memory function—prospective memory. Twenty-five MDMA users, 37 cannabis users, and 43 illicit substance-naïve controls were assessed on their substance use history and reported prospective memory performance as measured by the Prospective Memory Questionnaire (PMQ) using a web-based survey. There were significant differences between MDMA users and controls and cannabis users and controls on long-term episodic subscale of the PMQ. However, given the high prevalence of cannabis co-use by MDMA users, it was not possible to determine if MDMA use alone is associated with prospective memory performance. The substance use patterns of the sample were evaluated. Alcohol was the most used substance followed by tobacco, cannabis, and MDMA. The incidence of polydrug use was high, with all illicit substance use reporting having used at least two substances in their lifetime. The present study supports previous research into prospective memory deficits associated with substance use, and provides a basis for future research, particularly for elucidation of prospective memory deficits specific to MDMA use and further evaluation of substance use patterns.