Methods: It was a cross- sectional study on 130 top and middle managers affiliated with Tehran University of Medical Sciences. A valid and reliable questionnaire was applied for data collection. Pearson correlation was used analyzing data.

  Results: Main findings were implied statistical significance among similar to me effect and groupthink (p=0.005), and also similar to me effect and functional conflict ( p=0.001 ) and narcissism as well ( P<0.0001 ).

  Conclusion: According to significance of variables in the studied model among managers affiliated with Tehran University of Medical Sciences, it is recommended to inform managers about Inappropriate impacts of similar to me effects through educational courses and cultural changes.