Objective:To investigate the correlation between platelet distribution width(PDW)and cerebral microbleeds(CMB)in the middle-aged and elderly population.Methods:A total of 2 839 subjects who underwent cranial magnetic resonance imaging(MRI)examination at Lishui Hospital of Zhejiang University from May 2016 to December were enrolled in this cross-sectional study.According to MRI results, subjects were divided into the CMB group(n=525)and the non-CMB group(n=2 314). Clinical data and PDW levels were compared between the two groups.CMB-related factors were analyzed by using a logistic regression equation.A receiver operating characteristics(ROC)curve was drawn to analyze the value of PDW levels in predicting the incidence of CMB.Results:The percentage of males, the proportion of smokers, the number of subjects with diabetes and serum creatinine levels were higher in the CMB group than in the non-CMB group[(55.05%(289/525) vs.45.12%(1 044/2 314), 42.67%(224/525) vs.34.67%(802/2 314), 12.76%(67/525) vs.9.51%(220/2 314), (68.91±21.38)μmol/L vs.(66.45±15.40)μmol/L, all P<0.05]. PDW levels were higher in the CMB group than in the non-CMB group(15.52±2.49)% vs.(14.67±2.90)%, χ2=93.75, P<0.05). Multivariate logistic regression analysis showed that the PDW level was an independent risk factor for CMB in the middle-aged and elderly population( OR=1.13, P<0.05). The area under the ROC curve(AUC)of PDW in predicting the incidence of CMB was 0.582, and with 15.95% as the optimal threshold value, the sensitivity and specificity were 75.0% and 41.8%.Patients were divided into the high PDW sub-group(n=1 691)and the low PDW sub-group(n=1 083)based on the PDW cutoff at 15.95%.The number of CMB and the incidence of CMB were higher in the high PDW group than in the low PDW group(0.75 vs.0.48, 23.3% or 394/1 691 vs.12.1% or 131/1 083, χ2=30.37 and 51.28, P<0.05). Conclusions:PDW levels are high in middle-aged and elderly patients with CMB, and elevated PDW levels are an independent risk factor for CMB.