Objective: This study aimed to describe the expertise practice of nurse clinical transplant coordinators (CTCs) in organ transplantation medical care.Methods: To present the expertise practices of CTCs, we conducted a qualitative descriptive study using semistructured interviews. We performed an analysis according to analytical methods from the (Modified) Grounded Theory Approach (M-GTA) proposed by Kinoshita.Results: The expertise practice of CTCs was associated with 14 categories: [conscious communication toward compromise], [observation to understand actual intention], [conversation content that quickly notices the other’s reaction and changes], [engaging so that patients and families do not have regrets after a transplantation], [provide support for the self-determination process and advocate the decision], [autonomous judgment and timely response while assessing patient conditions], [coordination in response to changes in conditions], [assertive communication with physicians], [care that is aware of team medicine], [mediate to build trust between patients/families and medical staff], [long-term care as a permanent primary], [promoting self-monitoring by grasping the timing of guidance], [stepping forward to solve problems], and [evaluate their own ability appropriately and have humble attitude].Conclusions: CTC in Japan demonstrates expertise practice with decision support during transplant selection, coordination during the transplant process, and long-term continuing care. In addition, this study highlighted that CTCs in Japan had been conducting autonomous practice as a nurse and providing comprehensive care including patients, family members, and living donors. Our results clarified the experienced CTC’s expertise practices in all organ transplants and can be used to improve and assess the quality of care given by Japanese CTCs in the transplant process.