Objective To investigate the changes of microRNA-150 ( miR-150) in peripheral blood leukocytes in sepsis patients, and their relationship with expression of immune cytokines and sepsis severity. Methods The level of mature miR-150 was quantified by real-time reverse transcriptase-polymerase chain reaction (RT-PCR) and normalized to that of control miRNA, U6, in peripheral blood leukocytes of 40 patients with sepsis, 20 patients with systemic inflammatory response syndrome ( SIRS) , and 20 normal individuals. Serum concentrations of tumor necrosis factor alpha (TNF-α) and interleukin-10 (IL-10) were measured by enzyme-linked immunoabsorbent assay in all subjects. The sequential organ failure assessment ( SOFA) score systemwas used to evaluate the severity of sepsis. The relationships between miR-150 and the white blood cell count ( WBC) , TNF-α, IL-10 and SOFA score of the sepsis patients were analyzed. Results MiR-150 was stable for at least 5 days when specimen stored at 4 ℃ and the determination of miR-150 had a broad linear detecting range ( 6. 97-6. 97 ×104 pg/ μL RNA, the lowest detecting limit: 6. 97 pg/μL RNA,r=0.999) .MiR-150 expression in the peripheral blood leukocytes in the sepsis group was significantly lower than that in the healthy control group ( Plt;0.01) , while WBC, IL-10 and IL-10/TNF-α ratio were significantly higher ( Plt;0.05) . There was no significant difference in levels of miR-150, IL-10, IL-10/TNF-α ratio, and WBC between the sepsis group and the SIRS group (Pgt;0.05) . There was no significant difference in serum concentrations of TNF-α among three groups ( Pgt;0.05) . MiR-150 expression in non-survivor sepsis patients was significantly lower than that in survivor sepsis patients (Plt;0.05) , while serum IL-10 and IL-10/TNF-αratio were significantly higher (Plt;0.01) , but there was no significant difference in serum TNF-α between the non-survivor group and the survivor group ( Pgt;0.05) . There was significantly negative correlation between miR-150 and SOFA score, TNF-α and IL-10( r=-0. 619, - 0.457, -0. 431, Plt;0.05, respectively) , but no correlation between miR-150 and WBC ( r =-0. 184, Pgt;0.05) . There was no relationship between serum TNF-α, IL-10, IL-10 /TNF-α ratio or SOFA score ( Pgt;0.05) . Conclusions MiR-150 expression in the peripheral blood specimens is significantly decreased in sepsis patients. The expression level of miR-150 not only reflect the situation of inflammatory response, but also may be used as a prognostic marker in sepsis, as it can reflect the severity of sepsis in certain degree.