This 70-year-old male patient is a victim of colon cancer with liver metastases. He received a subcutaneous Port-A catheter implantation in the left subclavian vein for long-term chemotherapy. About one month after successful use, he complained of numbness sensation for hours after chemotherapy, but he would get better the following morning. Nuclear medicine scintigraphy by injecting radiopharmaceutical directly into the reservoir of Port-A catheter clearly demonstrated leakage from the sidewall of catheter. After removal of Port-A catheter, his clinical manifestations disappeared, and he tolerated subsequent chemotherapy well through peripheral intravenous administration. Conclusively, this procedure is not only easy to be performed, but an effective method to evaluate Port-A catheter function in vivo.