Background: Breast augmentation with autologous fat tissue (AFT) has several advantages compared to the use of breast prostheses. Potentially adding to these advantages is a method that may enhance the graft take and reduce resorption through cell enhancement with adipose-derived stem and regenerative cells (ADRCs). Use of cell-enriched fat graft with reconstruction shows promise but safety and efficacy data for aesthetic breast surgery is limited. Materials and Methods: This study is a prospective, single-arm, investigator-initiated clinical study evaluating the transplantation of AFT enriched with ADRCs in patients seeking an alternative to breast prostheses for breast augmentation. Twenty Japanese women, mean age of 33.9 years of age, were enrolled and treated at Cosmetic Surgery Seishin in Tokyo, Japan. Syringe liposuction with 3 mm cannulae was performed. Half of the AFT harvested was processed with the Celution® System yielding a 5 mL suspension of concentrated ADRCs. The remaining AFT was washed to remove blood and waste, enriched with the ADRCs, and injected into the breast mound in microdroplets in as many layers as possible to ensure the cell-enriched AFT was surrounded by vascularized tissue. Mammography was performed pre-operatively and 9 months post-operatively. Before and after photos were taken and Breast Measurement (BRM) was performed pre-operatively and at 2 weeks, 1, 3, 6, and 9 months post-operatively. Results: No serious or unexpected adverse events were reported, and the procedure was safe and well tolerated in all patients. Mean volume of fat graft injected was approximately 120 cc per breast. BRMs were stable by three months post surgery, and all improved from baseline. Nine months post surgery the BRM mean was 3.3 cm greater than before the surgery. Overall doctor and patient satisfaction was 65% and 75%, respectively. Two patients showed cyst formation (~1-2 cm) and calcifications only alongside the capsule on follow up mammography, with no other treatment emergent complications noted. Conclusions: The results of this twenty patient study show that ADRC-enriched fat grafting for breast augmentation using the Celution® System is safe and effective, with all patients showing BRM improvement after a single treatment, and minimal complications noted throughout the study. An additional 250 patients have been treated since completing enrollment for this study, and data for this patient series will also be presented.