Background: Colostomy care is a crucial technique that significantly contributes to the success of treatment. Patients often require long-term or lifelong adaptation to a colostomy. Nurses play a vital role in providing knowledge and accurate practical guidance on colostomy care, especially in the early stages. Adapting to changes in their bodies and learning how to care for a colostomy pose great challenges for patients. 
Objectives: This study aimed (1) to assess colostomy self-care knowledge among patients at the General Surgery Department of Tay Nguyen Regional General Hospital, and (2) to examine the relationship between demographic characteristics and patients’ knowledge of colostomy self-care. 
Research subjects and methods: A cross-sectional descriptive study was conducted on 90 patients who underwent colostomy surgery and met the inclusion criteria. Data were collected using a structured questionnaire and a colostomy care observation checklist, both adapted from validated instruments. Reliability testing was conducted before use. 
Results: The proportion of colostomy patients who had correct knowledge was 21.9%. Education level and ethnicity were significantly related to patients’ knowledge (p < 0.05). Other factors including age, gender, and occupation reported no significant difference between groups. 
Conclusion: Patients demonstrated insufficient self-care knowledge regarding colostomy. There is a need for strengthened and tailored educational interventions are needed to improve self-management, prevent complications, and enhance quality of life.