The aim of our study was to assess the relationship between haematological parameters and development of post-operative AF whether off-pump or on pump CABG cohort. Between December 2011 and May 2015 a total of 346 patients undergoing CABG were analysed for our study. Preoperative MPV values were higher in AF group than those remained in sinus rhythm. Postoperative hematologic parameters showed that MPV, PDW, Lymphocyte count, N/L Ratio were also higher in AF group than those remained in sinus rhythm. In the logistic univariate regression there weren't any hematologic predictors of the development of new-onset AF. In this study, we could not find any relationship between haematological parameters and post-operative development of AF.