Background: Scapular winging is a rare condition of the shoulder girdle that presents challenging treatment decisions for clinicians. To inform clinical practice, clinicians need guidance on what the best treatment decision is for their patients, and such recommendations should be based on the total evidence available. Therefore, the purpose of this review was to systematically review the evidence regarding nonsurgical management and tendon transfer surgery of patients with neurologic scapular winging due to serratus anterior (SA) or trapezius (TP) palsy. Methods: PubMed, Embase, Web of Science, Cochrane Library, Emcare, and Academic Search Premier were searched up to April 5, 2022, for studies reporting on clinical outcomes after nonsurgical management and tendon transfer surgery of scapular winging due to weakness of the SA or TP muscle. The Integrated quality Criteria for Review Of Multiple Study (ICROMS) tool was used to classify the quality of the studies. Primary outcomes were the fraction of patients with spontaneous recovery after nonsurgical management and improvement in shoulder function, pain scores, and shoulder scores after tendon transfer surgery. Data were pooled if data on the same outcome were available for at least 3 studies, using random-effects meta-analysis. Results: Twenty-three (10 moderate-quality [MQ] and 13 low-quality) studies were included. Six studies (3 MQ; 234 shoulders) reported on outcomes after nonsurgical management of SA palsy, whereas 12 (6 MQ; 221 shoulders) and 6 studies (1 MQ; 80 shoulders) evaluated the outcomes of tendon transfer for SA or TP palsy (1 study addressed both). Spontaneous recovery of scapular winging with nonsurgical management varied between 21% and 78% across studies after a median follow-up of 72 months. For surgical management of SA palsy, pooling data in a meta-analysis showed that patients on average improved by 47° (95% confidence interval [CI]: 34-61, P ≤ .001) in active forward flexion, had lower visual analog scale scores for pain (mean difference [MD]: −3.0, 95% CI: −4.9 to −1.0, P = .003), and had substantial improvements in American Shoulder and Elbow Surgeons (MD: 24, 95% CI: 9-39, P = .002) and Constant scores (MD: 45, 95% CI: 39-51, P ≤ .001). Patients with TP palsy on average improved by 36° (95% CI: 21-51, P ≤ .001) in active forward flexion after tendon transfer. Statistical pooling was not possible for other outcome measures as insufficient data were available. Conclusion: A substantial part of nonsurgically managed patients with scapular winging seem to have persistent complaints, which should be part of the information provided to patients. Data pooling demonstrated significant improvements in shoulder function, pain scores, and shoulder scores after tendon transfer surgery, but higher quality evidence is needed to allow for more robust recommendations and guide clinical decision-making on when to perform such functional surgery.@en