Adipose-derived stem cells (ASCs) can be isolated from human adipose tissue with the exceptional potential for differentiation into mature adipocytes. Utilization of this system is very promising in developing improved techniques to repair soft tissue defects. Current reconstructive procedures, especially after trauma and oncological surgery, transfer autologous soft tissue grafts having limitations. However, ASCs offer the ability to either generate soft tissue with no donor-site morbidity (with the exception of a minor loss of adipose tissue) or enhance the viability and durability of other grafts. This review will discuss the relevant properties of human adult adipose-derived stem cells for the regeneration of adipose tissue. Discussion will focus on the biology of ASCs, cell delivery vehicles/scaffolds useful in applying ASCs as a therapy, and suitable IN VIVO animal models for studying adipose tissue engineering. Also included is a description of the current clinical studies with ASCs in Europe and Asia.