Abstract Aim: This study aims to analyze the health-related quality of life (HRQoL) and safety outcomes in attention-deficit/hyperactivity disorder (ADHD) patients treated with cannabis-based medicinal products (CBMPs). Methods: Patients were identified from the UK Medical Cannabis Registry. Primary outcomes were changes in the following patient-reported outcome measures (PROMs) at 1, 3, 6, and 12 months from baseline: EQ-5D-5L index value, generalized anxiety disorder-7 (GAD-7) questionnaire, and the single-item sleep quality score (SQS). Secondary outcomes assessed the incidence of adverse events. Statistical significance was defined as p < 0.050. Results: Sixty-eight patients met the inclusion criteria. Significant improvements were identified in general HRQoL assessed by EQ-5D-5L index value...