Fibronectin (FN) is a major matrix protein that is involved in multiple processes. Its Cell I-Hep II domain is potentially useful in tumor therapy. Here, a recombinant fragment of FN with the Cell I-Hep II-IIICS71 domain, CH/71, was expressed in Escherichia coli. The CH/71 fusion protein consists of Cell I-Hep II domain and 19th to 89th amino acids of IIICS domain of FN. The expression level of CH/71 in E. coli was very high after induction with IPTG. Furthermore, CH/71 protein was largely found in the soluble fraction. It was readily purified by one-step heparin-agarose affinity chromatograph. The ability of CH/71 binding cells was about 8-fold of that of Cell I-Hep II domain FN.