Recently, with the increasing need for transitional care services in patients discharged from the hospital, registered dietitians are required to engage in and support patients with their admission and discharge process. This study aims to examine the current / actual circumstances and challenges in the patient discharge planning for registered dietitians. From July to August 2021, we conducted a self-administered, web-based questionnaire survey for 75 registered dietitians engaged in the discharge planning in inpatient medical institutions. The questionnaire included characteristics of registered dietitians, such as years of experience and frequency of engaging in dietary guidance according to disease. Additionally, participants were asked about the amount of time they have available for six activities related to the discharge process, including nutrition and dietary guidance at the time of discharge and their degree of confidence in the implementation of these. Using multiple regression analysis, the factors related to confidence for implementing the six activities were examined. Participants’ practices, challenges, and requests regarding provision of dietary guidance service in discharge planning were obtained through free descriptions, and summarized using the qualitative descriptive method. In order to enhance support for registered dietitians in discharge planning, it is suggested that it is necessary to strengthen not only skills based on years of experience, but also “time” and “collaboration” with interprofessional teams, patients’ families, and others surrounding patients from hospitalization to discharge.