In 53 of 56 VTE patients, the expressions of CD3 + , CD8 + , CD16 + +56 + and CD19 were separately or combinedly down-regulated or the CD4 + /CD8 + ratio was abnormal. These results imply the occurrence of VTE is closely related to the immune function. In the present study, CD16 + +56 + T cells and/or CD8 + T cells were decreased in 34 out of 56 VTE patients (60.7%). Down-regulation of CD16 + +56 + , CD8 + and/or CD19 was found in 39 out of 56 patients (69.64%). These findings indicate the symptomatic VTE is associated with the decrease of innate immunity and adaptive immunity in more than 2/3 of patients. Moreover, 53 VTE patients (94.6%) had one or more immune dysfunctions.