Abstract Introduction Medicinal cannabis has mixed evidence for treating anxiety and depression, yet patients frequently use it as a treatment. This observational study evaluated the effects of medicinal cannabis initiation in adults with clinically significant anxiety and/or depression over a 6-month period. Methods Adults with clinically significant anxiety and/or depression initiating medicinal cannabis use in Maryland, USA completed ecological momentary assessment (EMA) and longitudinal follow-up evaluations. Hospital Anxiety and Depression Scale (HADS) assessments were completed at baseline and 1, 3, and 6 months after medicinal cannabis initiation. EMA measures were completed at baseline and daily for 8 weeks after cannabis initiation with measures collected before each cannabis use and...