The 6B11VLVHCH3 is an anti-idiotype antibody to ovarian cancer. It can mimic the ovarian cancer-associated antigen OC166-9. We have previously expressed it in Escherichia coli. We now express the 6B11VLVHCH3 in a Chinese hamster ovary (CHO) cell system. The 6B11VLVHhCH3 sequence was amplified from the prokaryotic vector and cloned into the eukaryotic expression vector pSecTag2. The construct was transfected into CHO cells. Then the transfected monoclonal CHO cells were sequentially adapted to growth in serum-free medium. Functional differences between the antibody produced in E. coli or CHO cells were assessed. The antibody produced by CHO cells was able to both mimic ovarian cancer antigen and retain FC region functionality. Importantly, the antigen mimicry activity of 6B11VLVHhCH3 produced by CHO cells is approximately 20 times higher than antibody expressed by E. coli. This method of expression provides a safer and higher quality antibody for clinical drug development.