Abstract: Collagen in aqueous solution was modified with different dosages of oxidized sodium carboxymethylcellulose (OCMC) m(OCMC):m(collagen) = 0~10:1 as a cross-linking agent, and the corresponding modified collagen membranes were then prepared and characterized by various techniques. Results of Fourier transform infrared spectroscopic analysis indicated that the triple-helical structure of collagen was not demolished, but the hydrogen bonding among collagen molecules was weakened due to the introduction of cross-linking linkages. According to the results of differential scanning calorimetry, swelling and water contact angle tests, it was found that the collagen membrane possessed strikingly different physicochemical properties depending on the dosage of OCMC. When the ratio of OCMC/collagen is less than 5:1, the cross-linking between amino groups of collagen and aldehyde groups of OCMC increased significantly with the increase of OCMC dosage. Especially, at the 5:1 ratio of OCMC/collagen, both thermal denaturation temperature (T_d) and water contact angle (WCA) of collagen membrane were improved significantly from the original 86.6 ℃ and 87.0° to 98.4 ℃ and 105.0°, respectively, and the swelling ratio of collagen membrane was dramatically reduced from the original 880% to 448%. However, when the ratio of OCMC/collagen is more than 5:1, the increase of OCMC dosage has no remarkable effect on the physicochemical properties of collagen membrane. For example, as the OCMC/collagen ratio was multiplied from 5:1 to 10:1, the increased values of Td and WCA were only 2.5 ℃ and 3.1°, respectively, while the decreased value of swelling ratio was only 62%.