It has been previously demonstrated that human umbilical cord stroma-derived stem cells (HUCSCs) are competent to differentiate into adipocytes. However, controversies have arisen as to whether HUCSCs can become mature adipocytes or not, and to what extent these cells can be induced in adipogenic pathway. Here, we extensively analyzed their adipogenic potency with a structural and functional approach by determining lipid formation dynamics in concordance to adipocyte-specific markers. During a 35-day period, HUCSCs respond to adipogenic induction, at which point 88% of cells exhibited multilocular lipid granules (LGs) having a mean diameter of 3 mu m in round-shaped, F-actin-poor cells. Although the 1st week of induction did not generally display typical lipidogenic phenotypes, the degree of adipogenesis was dissected and confirmed by mRNA expressions of peroxisome proliferator-activated receptor gamma, C/EBP-beta, sterol regulatory element-binding transcription factor 1, adipophilin, stearoyl-CoA desaturase, glycerol 3-phosphate dehydrogenase 1, LIPE, adiponectin, and leptin. All markers tested were found elevated in various amounts (3-70-fold) around day 7 and reached a plateau after day 14 or 21 (5-335-fold). Perilipin as a surface protein around the LGs was confined exclusively to the enlarging LGs. Conclusively, we propose that after the termination of proliferation, HUCSCs possess the biochemical and cellular machinery to successfully differentiate into maturing adipocytes under adipogenic conditions, and this feature will ultimately allow these fetus-derived stem cells to be used for various therapeutic or esthetic purposes.