Purpose: This study was a descriptive study conducted to investigate the effects of intellectual capital on organizational performance of nurses in medium and small hospitals. Methods: Data were collected from 241 nurses working in medium and/or small hospitals located in G City from August 10 to September 17, 2011. The measurement tools were the Intellectual Capital scale and Organizational Performance scale. Data were analyzed using frequency, percentage, mean, standard deviation, t-test, one way ANOVA, Pearson correlation, and hierarchical regression with SPSS WIN 18.0 PC. Results: Intellectual capital composed of human, customer, and structure capital had significant effects on organizational performance of nurses working in medium and small hospitals and explained 50.4% of the variance. Conclusion: In order to promote organizational performance of nurses, nursing managers and administrators need to invest more resources into the intellectual capital of the system including human, customer, and structure capital.