Objective To investigate the effects of Sini Decoction（四逆汤） on immune function in patients with severe sepsis of Yin syndrome. Methods A total of 50 severe sepsis patients with Yin syndrome were adopted and randomly divided into an test group and a control group with 25 cases in each group. The control group was given conventional western medicine treatment

and the test group was given Sini Decoction（四逆汤） orally or gastric tube injections on the basis of treatment in the control group

once a day for 3 days. Human leucocyte antigen-DR on monocytes（mHLA-DR） level

T lymphocyte subsets

immune function indexes

inflammatory markers

partial pressure of oxygen

oxygenation index and blood lactate levels were tested before and after treatment for both groups. Meanwhile

the sequential organ failure assessment（SOFA） score

acute physiology

and chronic health status scoring system Ⅱ（APACHE Ⅱ） score

28-day survival rate

and health economic indicators of the patients were observed. Results There were no significant differences in the immunological indexes between the 2 groups neither before nor after treatment. After treatment

the procalcitonin（PCT） and arterial oxygen partial pressure levels of the test group in the treatment group were significantly higher than those of the control group（P<0.01）. The mHLA-DR

CH50

IgM of both groups were increased after treatment

while C-reactive protein

lactic acid levels

and APACHE Ⅱ scores were significantly decreased（P<0.05 or P<0.01）. There were significant differences in the levels of interleukin 6（IL-6）

oxygen partial pressure

and oxygenation index before and after treatment in the test group（P<0.01）. There were no drug-related adverse events during the trial. Conclusion The Sini Decoction（四逆汤） can improve oxygenation and some inflammatory reactions with safety of patients with severe sepsis and Yin syndrome

but regulating effects on the immunosuppression is not yet proven.