Thrombotic and thromboembolic complications have been shown to play a critical role in the clinical outcome of COVID-19. Emerging evidence has shown that exosomal miRNAs are functionally involved in a number of physiologic and pathologic processes MESHD. However, neither exosomes nor miRNAs have been hitherto investigated in COVID-19. To test the hypothesis that exosomal miRNAs are a key determinant of thrombosis MESHD in COVID-19, we enrolled patients positive for COVID-19. Circulating exosomes were isolated from equal amounts of serum SERO and levels of exosomal miRNAs were quantified. We divided our population in two groups based on the serum SERO level of D-dimer on admission. Strikingly, we found that exosomal miR-424 was significantly upregulated whereas exosomal miR-103a, miR-145, and miR-885 were significantly downregulated in patients in the high D-dimer group compared to patients in the low D-Dimer group (p<0.0001).