The objective of the study is to find out the effect of shark chondroitin on T lymphocyte subsets in cancer patients. Patients were divided into two groups. One group was treated with chemotherapy alone, and the other group was treated with chemotherapy plus shark chondroitin. Using immunofluorescence technique, T lymphocyte subsets in the peripheral blood were determined in two groups before and after chemotherapy. The results showed that CD4 +/CD8 + ratio increased in the patients received shark chondroitin. In the chemotherapy group, CD3 + had no change, but CD4 + decreased while CD8 + increased significantly. The results suggest that shark chondroitin could enhance immune function in cancer patients, especially during chemotherapy. The objective of the study is to find out the effect of shark chondroitin on T lymphocyte subsets in cancer patients. Patients were divided into two groups. One group was treated with chemotherapy alone, and the other group was treated with chemotherapy plus shark chondroitin. Using The immunofluorescence technique, T lymphocyte subsets in the peripheral blood were determined in two groups before and after chemotherapy. The results showed that CD4 +/CD8 + ratio increased in the patients received shark chondroitin. In the chemotherapy group, CD3 + had no change, but CD4 + decreased while CD8 + increased significantly. The results suggest that shark chondroitin could enhance immune function in cancer patients, especially during chemotherapy.