Objective To explore the correlation between hematocrit and slow coronary flow (SCF) in male patients. Methods We studied 205 patients with angiographically no more than one stenosis lt;40% in each major coronary artery who had admitted to the department of cardiology of the Beijing Anzhen Hospital Affiliated to Capital Medical University from August 2011 to August 2012. According to the level of hematocrit, 101 patients were classified into the trial group whose hematocrit was more 42.9%, while 104 patients into the control group whose hematocrit was no more than 42.9%. Clinical variables were analyzed and compared between the two groups. Results The age was younger in the trial group than the control group, whereas the levels of white blood cell count, mean platelet volume, triglyceride, low-density lipoprotein cholesterol, left anterior descending artery (LAD) and right coronary artery (RCA) TIMI frame count and the proportion of SCF in the LAD were higher in the trial group than in the control group (Plt;0.05). The results of correlation analysis showed that, LAD TIMI frame count (r=0.238, P=0.001), proportion of SCF in the LAD (r=0.206, P=0.003) and RCA TIMI frame count (r=0.209, P=0.003) were positively correlated with hematocrit. The results of multivariate analysis (using logistic regression with adjusted confounding factors such as age) showed that, LAD TIMI frame count (OR=1.031, 95%CI 1.006 to 1.056, P=0.014), proportion of SCF in the LAD (OR=1.919, 95%CI 1.038 to 3.547, P=0.038) were independently correlated with hematocrit. Conclusion The proportion of SCF in the LAD is independently correlated to hematocrit, which suggested that increased hematocrit may contribute to the pathophysiological change of SCF in male patients.