Background and Objective: Currently, nursing productivity is a critical factor in control costs in hospitals because nurses' works plays a basic role in quality care and affect organizations' successes. Management factor is recognized as effective factor that affects nurses' productivity.This study aimed to assess the effect of improvement of nursing managers’ professional competencies on their productivity. Materials and Methods: This semi-experimental study was done in one of teaching hospitals in Mashhad city in 2010 which randomly selected. Samples were 52 nurses who work in 10 units before and after intervention. Data were gathered by two questionnaires: Nurses' productivity and checklist to assess nursing managers' competency. Data were analyzed by SPSS program. Results: Findings revealed that 3.9% of nurses considered their productivity level high before period of intervention but 36.5% after intervention. Paired t-test showed that there was a significant difference in nurses' productivity between before and after intervention(p < 0.000). In general, there was no correlation between nurses' characteristics and their productivity. Conclusion: Management is one of the ways for improving nurses' productivity. According to results of this study using managers' development program can change management and leadership methods and this result to improvement of nurses' care and nurses’ productivity.