Objective To explore the possible mechanism of Xiaoyan Decoction（ 消岩汤） treating lung cancer cachexia. Methods Forty mice were randomized into healthy group

model group

Xiaoyan Decoction group and megestrol acetate group

10 mice in each group. Other groups except the healthy group were established lung cancer cachexia models by cancer cells inoculation. After successful modeling

mice in the model group were given normal saline 1ml by gavage every day. The Xiaoyan Decoction group was given Xiaoyan Decoction 0. 42 g by gavage every day. The megestrol acetate group was given megestrol acetate suspension 3. 75 mg / d by gavage every day

all group treated for 14 days. The weight of gastrocnemius was measured. The content of serum tumor necrosis factorα（ TNF-α） and interleukin 6（ IL-6）

expressions of muscular atrophy box F gene（ MAFbx） and muscle ring finger 1（ MURF-1） m RNA were detected. Results Compared with the healthy group

the weight of gastrocnemius in the model group decreased. The content of TNF-α and IL-6

as well as the expressions of MAFbx and MURF-1 m RNA in the model group and the megestrol acetate group increased（ P < 0. 01）. Compared with the model group

the weight of gastrocnemius in the Xiaoyan Decoction group increased. The content of serum TNF-α and IL-6

as well as the expressions of MAFbx m RNA and MURF-1 m RNA decreased（ P < 0. 05 or P < 0. 01）. The content of TNF-α and IL-6 in the megestrol acetate group decreased（ P < 0. 05）. The weight of gastrocnemius in the megestrol acetate group was much smaller than that in the Xiaoyan Decoction group（ P < 0. 01）; the level of serum TNF-α and IL-6

as well as the expressions of MAFbx and MURF-1 m RNA were higher than those in the Xiaoyan Decoction group（ P < 0. 05 or P < 0. 01）. Conclusion Xiaoyan Decoction may improve status of lung cancer cachexia through inhibiting the expressions of MAFbx and MURF-1 genes

improving muscle protein degradation and reducing inflammatory cytokines production.