Abstract Point-of-care (POC) testing has demonstrated great transformative potential in personalized medicine. In particular, patients undergoing transplantation require POC testing to ensure appropriate serum immunosuppressant levels so as to maintain adequate graft function and survival. However, no suitable POC device for monitoring immunosuppressant levels is currently available. Exploiting the latest advances in metamaterials can lead to a breakthrough in POC testing. A high-contrast grating (HCG) biosensor is a low-cost, compact, simple-to-fabricate, and easy-to-operate structure. It is highly sensitive and robust in surface-based biomarker detection, which is favorable for the efficiency of a POC device. In this study, the feasibility of using an HCG as a POC sensor for therapeutic drug monitoring of immunosuppressants was evaluated. The detection efficiency of the most commonly prescribed immunosuppressive medication cyclosporine A by using this sensor was demonstrated to be comparable to those of conventional commercial kits, suggesting that the sensor has the potential to be used as a rapid detection and feedback platform for increasing drug compliance and improving new organ transplant survival.