Objective      To determine the effects of hydrogen sulfide (H

2

S) on the myocardial fibrosis and the myocardial expression of nuclear factor-κB p65 (NF-κB p65) and tumor necrosis factor-α (TNF-α) in diabetic rats.       Methods      Thirty male adult rats were randomly divided into 3 groups: a control group

a diabetes mellitus group [streptozotocin (STZ) group

]

and a diabetes mellitus treated with H

2

S group (STZ+H

2

S group). The diabetic rat model was estab

lished by intraperitoneal injection (i.p.) of STZ at 40 mg/kg. The control group was treated with normal saline every day (i.p.)

and NaHS (100 μmol/kg

i.p.) as H

2

S donor was administered to the rats of the STZ+H

2

S group. After 8 weeks

the pathologically morphological changes of myocardial fibers were analyzed by HE staining

and the expression of type Ⅳ collagen

NF-κB p65 and TNF-α was analyzed by Western blotting.       Results      Compared with the STZ group

the interstitial fibrosis of myocardial cells was obviously alleviated after H

2

S intervention in the STZ+H

2

S group. Compared with the control group

the expression of type Ⅳ collagen

NF-κB p65 and TNF-α was significantly increased in the STZ group (P0.05). However

H

2

S treatment reversed the STZ-induced up-regulation of type Ⅳ collagen

NF-κB p65 and TNF-α in the STZ+H

2

S group.       Conclusion      H

2

S alleviates myocardial fibrosis in the diabetic rats through inhibiting the NF-κB p65 and TNF-α signaling pathway.