Purpose: The purpose of this study was to examine nurses’ knowledge of constipation and nursing activities for older patients and to identify nurse characteristics differentiating knowledge and activities. Methods: Data were gathered through a questionnaire survey of 200 nurses from 29 hospitals with more than 150 beds. Cronbach's ⍺ was .623 for constipation knowledge and .806 for nursing activities. Data were analyzed using descriptive statistics, t-test, ANOVA, and Duncan test. Results: Average percentage of correct answer was 64.0% with the highest percentage (78.3%) in the area of causative factors. Of nursing activities for constipation, 91% of the nurses reported that keeping a daily elimination record and assessing patient status were performed frequently. Total score of knowledge differed significantly by hospital size, experience of education, use of resources, and interest about nursing activities for constipation in older patients. The frequency of nursing activities was significantly different according to nurses' interests in nursing activities for older patients with constipation. Conclusion: The study findings indicate that in-service training programs should be developed to increase constipation knowledge and performance of nursing activities to alleviate constipation among older patients in long-term care hospitals. Administrative support is also required to increase nursing time for patient care.