Objectives: Spinal muscular atrophy (SMA) is a rare genetic disorder that causes progressive muscle weakness and paralysis. In its most common and severe form, the majority of untreated infants die before 2 years of age. Early detection and treatment, ideally before symptom onset, maximize survival and achievement of age-appropriate motor milestones, with potentially substantial impact on health-related quality of life. Therefore, SMA is an ideal candidate for inclusion in newborn screening (NBS) programs. We evaluated the cost-effectiveness of including SMA in the NBS program in The Netherlands. Methods: We developed a cost-utility model to estimate lifetime health effects and costs of NBS for SMA and subsequent treatment versus a treatment pathway without NBS (ie, diagnosis and treatment after presentation with overt symptoms). Model inputs were based on literature, local data, and expert opinion. Sensitivity and scenario analyses were conducted to assess model robustness and validity of results. Results: After detection of SMA by NBS in 17 patients, the number of quality-adjusted life-years gained per annual birth cohort was estimated at 320 with NBS followed by treatment compared with treatment after clinical SMA diagnosis. Total healthcare costs, including screening, diagnostics, treatment, and other healthcare resource use, were estimated to be €12 014 949 lower for patients identified by NBS. Conclusions: NBS for early identification and treatment of SMA versus later symptomatic treatment after clinical diagnosis improves health outcomes and is less costly and, therefore, is a cost-effective use of resources. Results were robust in sensitivity and scenario analyses.