Aim: To investigate whether there is a relationship between both massive and sub-massive pulmonaryembolism (PE) and eosinophil counts in order to evaluate it as a predictor factor.Methods: This retrospective study included 108 patients (64 sub-massive and 44 massive) who received bothtomographic and clinical diagnoses of pulmonary embolism, and 75 subjects served as controls. Hemogramparameters were compared between patients with massive and sub-massive pulmonary embolism and those ofcontrol groups. Results: In terms of white blood cell and eosinophil counts, the lowest value was evident in the massive PEgroup whereas the control group had the highest value. The eosinophil counts increased significantly one weekafter the treatment when compared to those at the presentation with PE (0.112 (0.003-0.853) vs. (0.144 (0.011- 0.914), p=0.01). Spearman correlation test showed a significant positive correlation between right ventricular dysfunction or elevated cardiac troponin level and massive PE (r=0.54, p <0.001), whereas a negativecorrelation was detected between eosinophil count and the presence of massive PE (r=-0.36, p<0.001). Conclusion: The results of our study suggest that lower eosinophil counts may lead a physician to suggest ahigher probability of acute massive pulmonary embolism rather than sub-massive pulmonary embolism. However, further randomized studies are required to confirm these findings.