[SUMMARY] Objectives : To reveal nursing practices to prevent dehydration-related urgent hospitalization of cancer patients receiving outpatient chemotherapy and to indicate effective nursing practice that enable patients to make appropriate situational decisions and take the initiative in their own behaviors. Methodology : Semi-structured interviews were conducted with seven nurses who work at a regional cancer hub hospital and have experiences in treating walk-in and/or urgently-hospitalized patients who have received chemotherapy for over five years. Acquired data were analyzed qualitatively and inductively. Results : The following nursing practices were revealed : 1. collection and assessment of information on cancer patient characteristics associated with risks and prevention of dehydration risks ; 2. provision of information for the prevention of dehydration in patients ; 3. sharing of issues and solutions with patients for preventing dehydration ; 4. supportive assistance from nurses based on accurate awareness of patients’ self-management capacities in relation to dehydration prevention ; 5. support in preparation for the onset of dehydration symptoms and emergency situations ; 6. establishment of patientnurse relationships through education on dehydration prevention ; and 7. self-reflection on nursing practices and trials in practices. These results and discussions suggest the necessity of effective nursing practice, including: enrichment of medical records and collaboration/cooperation with other professions and departments to grasp an overall picture of patient status ; self-management assistance to enhance patient autonomy in accordance with their learning stages; and improvement in thenursing practice capabilities of nurses for comprehensive decision making.