BACKGROUND:Adipose-derived stem cells are easily col ected and abundantly cultured, which can proliferate rapidly when being cultured in vitro. With multi-directional differentiation potential, adipose-derived stem cells are expected as seed cells for tissue engineering. OBJECTIVE:To isolate, culture and identify of adipose-derived stem cells from Sprague-Dawley rats in vitro. METHODS:The subcutaneous adipose tissue was obtained from the iliac region of rats under the aseptic condition, and then was digested with 0.075%type Ⅰ col agenase and cultured in vitro. The morphology and proliferation characteristics of the cells were observed under an inverted phase contrast microscope. The third passage was put into gauge for growth curve by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide, and the cells were also identified by CD44, a stem cellmarker, with immunofluorescence staining. Adipose-derived stem cells were induced and differentiated into adipocytes in Dulbecco’s modified Eagle’s medium/Ham’s nutrient mixture F-12 containing 10%fetal bovine serum, dexamethasone and insulin, and then the cells were identified with oil red“O”staining. Adipose-derived stem cells were induced and differentiated into neural cells, and then the cells were identified with immunohistochemical staining. RESULTS AND CONCLUSION:The growth curve of adipose-derived stem cells was opposite-like“S”shape, and it strongly expressed CD44 that can designate a stem cell. The passage cells were exposed to a defined medium for adipocyte differentiation, and then could be stained with oil red. After being induced and differentiated into nerve cells, the cells expressed neuron-specific enolase. The adipose-derived stem cells of Sprague-Dawley rats are characterized by easy isolation, culture and proliferation in vitro, expressing related phenotypes of mesenchymal stem cells, as wel as induction and differentiation under certain conditions.