Introduction: Nurses, as one of the main sources of organizational knowledge and main elements of knowledge transfer in hospitals, can play a key role in organizational learning process. The present study was performed due to the importance of organizational learning capabilities of nurses. Objective: This study aimed to investigate the effectiveness of decision-making through brainstorm on organizational learning capability in nurses. Material and Methods: This study was conducted in two stages: In the first stage, learning capability of all nurses in internal-surgical section (18 departments) of Baqiyatallah Hospital was measured by census method (281 persons). In the second stage, eight sections with no significant differences in organizational learning were determined and randomly divided into test and control groups. A theoretical and practical training workshop was held to train other personnel and head nurses how to implement the brainstorming method for decision making. Then, after four months, the Organizational Learning Questionnaire was distributed in control and test groups. Data analysis was done through descriptive statistics including mean±standard deviation (SD) and analytical statistics including Chi-square, Mann-Whitney, Wilcoxon, T-test and ANOVA using SPSS.19. Results: The results of the first stage showed that the mean of total score for organizational learning capability of nurses was 58.04 (8/98), which according to Likert scale, was average. Also, the mean of scores for areas of management commitment, system and knowledge transfer was 19.02 (33.23), 11.44 (1.88) and 13.67 (3.05), respectively which was average, while that was 13.89 (2.80) for the fields of open space and experiment, which was at the lowest level. The results of the second stage of the study showed that the meanof total score in entire area of organizational learning capability in nurses increased and was significantly different before and after running the intervention and brainstorming in the test group.For example, the standard deviation of the entire organizational learning capability in nurses was p = 0.012 after the intervention. Also, the standard deviation of areas of management commitment,, System Attitude and knowledge transfer was p=0/044, p=0/000, and p=0/003, respectively, that were all significant, but no difference was observed in the control group. Discussion and Conclusion: According to the results of this study and the effectiveness of brainstorming method on boosting the organizational learning capability of nurses and improving the quality of nursing care and nursing services, it is recommended that the nursing managers implement this method in health care departments.