Background and Objective: Conflicts among health care personnel including nursing personnel who require extensive interaction with different people, is common and almost inevitable. As there is not sufficient information about the causes, types, and dimensions of interpersonal conflicts among clinical nurses and the adverse effects of these conflicts on the function of nursing team in Iran, we aimed to perform this study in order to find out causes of different inter-group or inter personal conflicts among nurses using qualitative research method and Grounded Theory Approach (GT). Materials and Methods: The data was collected through interviews. Constant comparison method was used in order to perform qualitative analysis. Results: Open coding process resulted in emergence of causal conditions and different types of conflicts within the nursing society. Exposure to imposed conditions, confronting with opposition, disagreement and destructive behaviors were indicative of characteristics of conflicting events and tasks, process, relational and marginal conflicts which were major categories of conflict in clinical settings. Feeling threats towards benefits was recognized as the main apprehension of participants. This core variable can explain how conflicts occur and develop within nursing society according to conflicts of benefits. Conclusion: The findings showed that individual factors and intra as well as extra-organizational factors were major and/or contextual causes of inter-group conflicts among nurses. One of the significant and interesting findings in this study was that the conflicts did not affect the occupational function of nurses despite the significant effect on marginal issues in their work environment. The study also showed that these conflicts are part of simulation process in nursing tasks. Key words: Occupational Conflicts, Interpersonal Conflict, Nursing, Clinical Environment.