Human adipose tissue provides a uniquely abundant and accessible source of adult stem cells for applications in tissue engineering and regenerative medicine. The adult stem cells are isolated by collagenase digestion, differential centrifugation and subsequent adherence to a plasticware surface. Based on their immunophenotype, the cells are relatively homogeneous, with shared expression of integrin beta(1), the hyaluronate receptor, and the tetraspan protein CD9, among other markers. In response to chemical, hormonal or structural stimuli, the adipose-derived adult stem (ADAS) cells can differentiate along multiple lineage pathways, including adipocytes, chondrocytes, myocytes, neurons and osteoblasts. The cells can be transduced with viral vectors and have potential utility as gene delivery vehicles. Further studies will facilitate the clinical and commercial development of ADAS cells. First, it will be necessary to develop closed system bioreactors for the large-scale manufacture of ADAS cells. Second, methods that improve the vascularisation of in vivo implants will allow transplantation of larger engineered tissues. Finally, experiments must investigate the feasibility of transplanting allogeneic, as compared to autologous, ADAS cells for therapeutic applications. Based on the promising findings from adipose-derived and other adult stem cells to date, it is likely that future studies will address these challenges.