This narrative review examines whether the endocannabinoid system may play a biochemical role in ADHD pathophysiology. It gathers 11 preclinical and 2 clinical studies and argues that ECS signaling may intersect with attention, impulsivity, and hyperactivity pathways. The core limitation is that the evidence remains thin, heavily preclinical, and far from proving that cannabinoid-based treatments are ready for clinical use in ADHD.