Abstract. Mean platelet volume (MPV), a marker of platelet activation, is a surrogate marker of platelet function and a potential mediator of the association between inflammation and thrombosis. The present retrospective study sought to investigate the association between MPV and the presence of thrombotic events (TEs) in patients with chronic atrial fibrillation (AF). A total of 114 consecutive patients with chronic AF were enrolled from a Chinese hospital. Individuals were divided into three groups: The AF+TE group (n=57, 33.1%), which comprised patients in AF with concomitant TEs; the AF group (n=57, 33.1%), which comprised patients in AF with no identifiable TEs, as confirmed by brain computed tomography, transesophageal echocardiography, or a combination of the two; and a control group (n=58, 33.7%), which consisted of patients who were in sinus rhythm. MPV, high-sensitivity C-reactive protein (hsCRP), D-dimer and the left atrial diameter (LAD) were analyzed in the 172 participants. The MPV level of patients in the AF+TE group was significantly higher than that of patients in the AF and control groups (P<0.05). In the correlation analysis, MPV levels were found to be positively correlated with LAD, D-dimer concentrations and hsCRP levels in patients with AF (r=0.960, P<0.05; r=0.896, P<0.05; and r=0.924, P<0.01, respectively). In the receiver operating characteristic curve analysis, the value for MPV levels required to detect TEs with a sensitivity of 77.5% and specificity of 78% was 10.5 femtoliter (fl). A high MPV level (>10.5 fl) was significantly associated with the occurrence of TEs (odds ratio, 3:1; 95% confidence interval, 1.6-5.1; P=0.000). The results of the present study suggest that an additional biomarker, MPV, has a predictive value for the presence of TEs in patients with AF. MPV may be a potential mediator between inflammation and thrombosis.