The 2000–2001 and the 2022–2023 Taliban opium bans were and could be two of the largest ever disruptions to a major illegal drug market. To help understand potential implications of the current ban for Europe, this paper analyzes how opioid markets in seven Baltic and Nordic countries responded to the earlier ban, using literature review, key informant interviews, and secondary data analysis.The seven nations’ markets responded in diverse ways, including rebounding with the same drug (heroin in Norway), substitution to a more potent opioid (fentanyl replacing heroin in Estonia), and substitution to one with lower risk of overdose (buprenorphine replacing heroin in Finland). The responses were not instantaneous, but rather evolved, sometimes over several years.This variety suggests that it can be hard to predict how drug markets will respond to disruptions, but two extreme views can be challenged. It would be naive to imagine that drug markets will not adapt to shocks, but also unduly nihilistic to presume that they will always just bounce back with no lasting effects. Substitution to another way of meeting demand is possible, but that does not always negate fully the benefits of disrupting the original market. Nonetheless, there is historical precedent for a European country's opioid market switching to synthetic opioids when heroin supplies were disrupted. Given how much that switch has increased overdose rates in Canada and the United States, that is a serious concern for Europe at present. A period of reduced opioid supply may be a particularly propitious time to expand treatment services (as Norway did in the early 2000s).