We have continued to evaluate a second generation anti-TAG-72 antibody. This antibody, CC-49, recognizes TAG-72 the same antigen recognized by B72.3. We have imaged patients with lung carcinoma and one patient with colorectal carcinoma. The biodistribution is similar to that of I-131 B72.3. At present the number of patients is small to make comparisons between CC-49 and B72.3. We have studied one patient with I-131 B72.3 chimeric antibody. As expected the halflife in circulation of the chimeric is longer than that of the murine I-131 B72.3 counterpart.