Lake S, Walsh Z, Kerr T, et al. - In this longitudinal analysis, data from individuals in two prospective cohorts of people who use drugs (PWUD) in Vancouver, Canada, who reported major or persistent pain from June 1, 2014, to December 1, 2017 (n = 1,152) was involved in order to examine the longitudinal relationship between frequency of cannabis use and illegal opioid use among PWUD experiencing chronic pain. In comparison with cannabis non-users, Cannabis every day had about 50% lower odds of using illicit opioids every day. Individuals who reported occasional use of cannabis were not more or less plausible vs non-users to use illicit opioids on a daily basis. Compared with occasional cannabis users, daily cannabis users were more inclined to report a number of therapeutic uses of cannabis including for pain, nausea, and sleep. Thus, among PWUD with chronic pain, an independent negative correlation between persistent cannabis use and numerous illegal opioid use was discovered. Hence, results propose longitudinal observational evidence that cannabis could serve as a supplement to or replacement for illegal opioid use among PWUD with chronic pain.