Introduction: Free flap breast reconstruction (FFBR) restores body image and improves quality of life in women post mastectomy. Sarcopenia, defined as depletion of skeletal muscle, reflects declining physiologic reserve, regenerative capacity, and impaired immunologic competence. A systematic review was conducted to assess whether sarcopaenia is a predictor for complications in FFBR. Metholodogy: A MEDLINE, PubMed, Cochrane and EBSCO Host search was conducted regarding the effects of sarcopaenia on FFBR. Outcomes evaluated included wound complications, flap loss, and thromboembolic events. Donor related complications include infection, hematoma and abdominal wall weakness, while flap related complications include wound problems and return to theatre. Result: 6 studies with a total of 1473 patients met the inclusion criteria and were included. 465 patients met the definition of pre-operative sarcopenia. Sarcopenia significantly increases the rate of overall complications (15.0% - 92.3%, p<0.05), flap delayed healing (17.5%, p=0.046), take back to OR (13.4% p=0.05), ICU stay (p<0.0005), length of hospital stay (2.89 days, p<0.0005). Furthermore, sarcopaenia was a stronger predictor than BMI for perioperative complications (p<0.05). Despite heterogeneity between studies, all except one demonstrated significant correlation between sarcopaenia and perioperative complications in FFBR. Conclusion The current literature demonstrates that sarcopenia is superior to BMI in predicting complications in FFBR, with important clinical implications in patient selection and counselling. Future studies should investigate whether preoperative improvements in sarcopenia scores translate to minimisation of perioperative complications.