Purpose: Fat grafting has shown many benefits in mitigating radiotherapy induced soft tissue injury. However, little research has been done to determine the direct effects of radiotherapy on adipose derived stem cells (ADSCs), the regenerative constituents of fat graft. We present an invitro study which firstly, focuses on interrogating key homeostatic functions of ADSC and secondly, by exploring the molecular alterations resulting from 10Gy irradiation of ADSC compared to 0Gy controls. Methods: Functional homeostatic assays were conducted comparing proliferation, apoptosis, migration and adipogenic differentiation of control 0Gy and irradiated 10Gy ADSC. Molecular analysis included next generation sequencing and qualitative polymerase chain reaction analysis of adipogenic differentiation genes. Results: The results in this presentation demonstrate the adverse impact of radiotherapy injury to ADSCs. The reduction in proliferation as well as apoptosis demonstrates that irradiated ADSC, like endothelial populations, acquire a state of senescence and persist as cells unable to successfully perform key homeostatic functions. The diminished capacity of irradiated ADSC migration and adipogenic differentiation all represent significant impairment in the capabilities of these cells to carry out their regenerative functions. Conclusion: Radiation impairs loco-regional ADSC function, therefore requiring the introduction of healthy adipose tissue and ADSC through fat grafting to reconstitute this cell group’s functions. Future research involves manipulation of key molecular and metabolomic candidates to further improve the microenvironment and attempt to mitigate radiotherapy injury to both targeted and grafted ADSC.