Objective To explore the potential mechanism of Anchang Decoction（安肠汤） in treating ulcerative colitis. Methods One hundred and twelve rats were randomized into blank group

model group

Mesalazine group

Live Bifidobacterium group and Anchang Decoction high

medium and low dose groups

with 16 rats in each group. Ulcerative colitis model was built in each group except for the blank group. Ten days after modeling

the blank group and the model group were given oral administration of 3 ml of normal saline; Live Bifidobacterium group was given 0. 12 ml of oral Live Bifidobacterium preparation（50 million viable bacteria/ml）; Mesalazine group was given0. 35 ml of Mesalazine suspension（5 mg/ml） by gavage; and Anchang Decoction low

medium and high dose groups were respectively given 1

5

or 10 ml/（kg·d） of concentrated Anchang Decoction. All treatments were given once daily for 10 days. The lesion segment of colon was harvested for HE staining to observe the histomorphology of colonic mucosa. The stool samples were collected from each group to determine the intestinal fungal contents（including Candida albicans

Aspergillus

Penicillium

Cladosporium and Cryptococcus） with real-time fluorescence quantitative technology. Results The results of HE staining showed that the colonic mucosa in the model group was almost completely absent

with ulceration

mucosal erosion and inflammatory cell infiltration

while colonic mucosa in the treatment groups all improved compared with that in the model group. Compared with those in the blank group

the relative expression levels of Candida albicans

Aspergillus and Penicillium significantly increased

while the relative expression levels of Cladosporium and Cryptococcus decreased in other groups（P < 0. 05）. Compared with those in the model group

the relative expression levels of Candida albicans

Aspergillus and Penicillium significantly decreased

while the relative expression levels of Cladosporium and Cryptococcus significantly increased in each of treatment groups（P < 0. 05）. Effects were better in Anchang Decoction medium dose group than in Anchang Decoction low and high dose groups in reducing relative expression level of Aspergillus and raising expression levels of Cladosporium and Cryptococcus

while effects were better in Anchang Decoction high dose group than in Anchang Decoction low and medium dose groups in reducing the relative expression levels of Candida albicans and Penicillium（P < 0. 05）.Conclusion Anchang Decoction seems have a clear regulatory effect on intestinal fungi in rats with ulcerative colitis

which may be one of its mechanisms in the treatment of ulcerative colitis.