The purpose of this study was to investigate correlation with self-care behaviors and physiological index according to cognitive function of hemodialysis patients. The data were collected from 108 patients on hemodialysis in university hospital. The period of data collection was from January 4 to January 31, 2010. The instruments of research were MMSE, Self-care behavior scale for hemodialysis patients. The 17.6% of patients showed the cognitive disorder. Self-care behaviors of patients showed that normal cognitive function group was significantly higher than dysfunction group. Creatinine and parathyroid hormone of patients showed that normal cognitive function group was significantly lower than dysfunction group. The cognitive function of patients showed positive correlations with self-care behavior(r=.283, p=.003) and Kt/V(r=.214. p=.026), showed significant negative correlations with phosphorus(r=-.223, p=.020) and creatinine(r=-.318, p=.001). The results of this study can be used to develop nursing education program to improve self-care behaviors according to cognitive function of hemodialysis patients.