This study was conducted to examine the clinical factors which affected the amount and the duration of infusion of intravenous (IV) heparin on ischemic stroke. Method: A cross-sectional descriptive study was designed to examine the factors. A total of 101 patients with ischemic stroke from a University hospital in G-city, Korea from January to December, 2006 were participated in this study. Data were analyzed by t- and ANOVA test, correlation coefficient, and stepwise multiple linear regression analysis. Result: This study showed that the patients who have been temporarily stopped to infuse iv heparin for more than one hour, had cardioembolic stroke, and had the lower count of initial red blood cell (RBC) had significantly lower amount of iv heparin infusion per body surface. In addition, this study founded that the patients with lower count of initial RBC and the lower level of initial blood sugar were significantly less likely to have the lower length of iv heparin infusion. Conclusion: Continuous monitoring and controlling the count of RBC and the level of blood sugar are needed to increase the efficacy of iv heparin therapy on ischemic stroke. Further empirical studies should be conducted to support the results of this study.