Hallucinogen Persisting Perception Disorder (HPPD) is considered rare in hallucinogen users although there are conflicting reports about its incidence and prevalence. HPPD may be more common in those with trait neuroticism. In this study, we invited hallucinogen and other drug users to complete an online questionnaire about their use of hallucinogens, their experience of HPPD symptoms, and their trait neuroticism and mental health symptoms. We received 802 responses with 415 of these containing adequate data for further analysis. 39.7% of responders reported symptoms corresponding to Type I HPPD, and 4.3% reported symptoms corresponding to Type II HPPD. We found no significant difference between neuroticism scores for participants with or without HPPD. Individuals with Type II HPPD were more likely to report mental health symptoms including anxiety, obsessional thoughts, paranoia, hypochondria and panic attacks (