Collagen, the most abundant protein in vertebrates, is a useful biomaterial in pharmaceutical and medical industries. So far, most collagen has been extracted from animals and cadavers. Herein, we suggest human adipose tissue, which is routinely abandoned after liposuction, as a plentiful source of human collagen. In this study, human collagen was obtained from adipose tissue through two successive major steps: (i) extraction of the extracellular matrix (ECM) by pulverization, centrifugation, alkaline, and alcohol treatment; (ii) isolation of collagen from ECM by pepsin treatment in dilute acetic acid. The purified human adipose-derived collagen was characterized by Fourier transform infrared spectroscopy, polyacrylamide gel electrophoresis, amino acid analysis, and circular dichroism spectroscopy. The extracted collagen showed a typical triple helix structure, good thermal stability due to abundant imino acids, and high solubility at acidic pH. The collagen greatly facilitated the adhesion and proliferation of human adipose-derived stem cells and normal human dermal fibroblasts on polystyrene plates. These results suggest that human adipose tissue obtained by liposuction can provide human collagen for use in cosmetics, pharmaceutics, and medicine. (c) 2012 American Institute of Chemical Engineers Biotechnol. Prog., 28: 973980, 2012