Attempts to identify opioid users with increased risk of escalating to opioid use disorder (OUD) have had limited success. Retrospectively assessed subjective effects of initial opioid misuse were compared in a pilot sample of opioid misusers (nonmedical use ≤60 times lifetime) who had never met criteria for OUD (N = 14) and heroin-addicted individuals in treatment for OUD (N = 15). Relative to opioid misusers without a lifetime OUD diagnosis, individuals with OUD reported greater euphoria and other positive emotions, activation, pruritus, and internalizing symptoms. Consistent with these findings, proxy Addiction Research Center Inventory (ARCI) Amphetamine Group, and Morphine Benzedrine Group scale mean item scores were significantly higher in those with OUD. Replication was attempted in opioid misusers with (N = 25) and without OUD (N = 25) who were assessed as part of an ongoing genetic study. We observed similar significant between-group differences in individual subjective effect items and ARCI scale mean item scores in the replication sample. We, thus confirm findings from prior reports that retrospectively assessed subjective responses to initial opioid exposure differ significantly between opioid users who do, and do not, progress to OUD. Our report extends these findings in comparisons limited to opioid misusers. Additional research will be necessary to examine prospectively whether the assessment of subjective effects after initial use has predictive utility in the identification of individuals more likely to progress to OUD.