Background <p>Cannabis use has been increasingly associated with acute coronary syndromes in young adults without conventional cardiovascular risk factors. The psychoactive compound Δ⁹-tetrahydrocannabinol (THC) exerts sympathomimetic, endothelial, and prothrombotic effects that may precipitate myocardial infarction through platelet activation and vasospasm.</p> Case presentation <p>A 34-year-old man, a chronic cannabis user, presented with acute anterior ST-segment elevation myocardial infarction. Coronary angiography demonstrated a large thrombus involving the left main and proximal left anterior descending arteries, with complete mid-LAD occlusion (TIMI 0). In view of the extensive thrombus burden, 300,000 International units of intracoronary streptokinase followed by 1,200,000 IU intravenously was administered, resulting in significant thrombus resolution and restoration of TIMI II flow. The patient recovered uneventfully on dual antiplatelet therapy, statin, and anticoagulation.</p> Discussion <p>Cannabis associated thrombosis may involve multiple interrelated mechanisms: (i) catecholamine surge with tachycardia and vasospasm, (ii) endothelial dysfunction, and (iii) direct platelet activation via CB₁ and CB₂ receptors leading to increased thromboxane A₂ and P-selectin expression. This case illustrates a possible association between chronic cannabis exposure and large-vessel thrombosis in the absence of significant angiographic atherosclerosis. Intracoronary fibrinolysis may be considered in selected cases with prohibitive thrombus load where primary PCI is unsafe.</p> Conclusion <p>This case underscores the prothrombotic potential of cannabis and highlights the need to recognize its cardiovascular risks. Understanding the cannabinoid–platelet–vascular axis may help prevent and manage cannabis-related coronary events.</p> Clinical trial registration <p>Not applicable as not a clinical trial.</p>