Multiple sclerosis (MS) represents a spectrum of demyelinating presentations with varying degrees of inflammatory activity and symptom expression, affecting nearly one million individuals in the U.S. The use of Food and Drug Administration (FDA)-approved disease-modifying therapies (DMTs) aim to reduce risk for clinical exacerbations, MRI activity, and neurological disability. Currently, more than 20 FDA approved DMTs for the treatment of MS are now approved, including four generic oral agents: cladribine, dimethyl fumarate, fingolimod, and teriflunomide. Additionally, the first biosimilar agent, natalizumab, recently became commercially available for use in the U.S. Nationwide, health insurance utilization management policies frequently require newly diagnosed individuals with MS to initiate treatment with one or more generic DMTs before authorization of a branded agent is granted or mandate transition from a branded agent to a generic alternative despite clinical stability. Expanded use of generic DMTs is also anticipated with the recent change in the MS diagnostic criteria. Recent data indicated that some generic DMTs contain levels of active ingredient below FDA good manufacturing standards. Less is known if generic DMTs are bioequivalent to innovator brand name products. This presentation will provide i) general information related to the U.S. FDA regulatory standards for generic and biosimilar medications, ii) a summary of recent published data involving the quality and clinical outcomes associated with MS generic DMTs, iii) a mechanistic framework describing how variations in generic drug quality may influence disease control, and iv) possible solutions to improve therapeutic monitoring to ensure consistent treatment efficacy and patient safety. Level of Information: Basic, Intermediate, AdvancedMultiple sclerosis (MS) represents a spectrum of demyelinating presentations with varying degrees of inflammatory activity and symptom expression, affecting nearly one million individuals in the U.S. The use of Food and Drug Administration (FDA)-approved disease-modifying therapies (DMTs) aim to reduce risk for clinical exacerbations, MRI activity, and neurological disability. Currently, more than 20 FDA approved DMTs for the treatment of MS are now approved, including four generic oral agents: cladribine, dimethyl fumarate, fingolimod, and teriflunomide. Additionally, the first biosimilar agent, natalizumab, recently became commercially available for use in the U.S. Nationwide, health insurance utilization management policies frequently require newly diagnosed individuals with MS to initiate treatment with one or more generic DMTs before authorization of a branded agent is granted or mandate transition from a branded agent to a generic alternative despite clinical stability. Expanded use of generic DMTs is also anticipated with the recent change in the MS diagnostic criteria. Recent data indicated that some generic DMTs contain levels of active ingredient below FDA good manufacturing standards. Less is known if generic DMTs are bioequivalent to innovator brand name products. This presentation will provide i) general information related to the U.S. FDA regulatory standards for generic and biosimilar medications, ii) a summary of recent published data involving the quality and clinical outcomes associated with MS generic DMTs, iii) a mechanistic framework describing how variations in generic drug quality may influence disease control, and iv) possible solutions to improve therapeutic monitoring to ensure consistent treatment efficacy and patient safety. Level of Information: Basic, Intermediate, Advanced