The purpose of this study was to investigate the effect of Brousson etiae fructus (BF) on the urethral nitrite level and the urethral nitric oxide synthase (NOS) activity in streptozotocin (STZ) induced diabetic rats. In vitro, the urethral NOS activity was not noted in the level of Dose of extract prepared from BF. In vivo, the urethral NOS activity was increased in normal rats and STZ induced diabetic rats by dose and term of extract prerared from BF. The the NOS activity decreased in STZ induced diabetic rats was increased as highly as norma1 group by the extract of BF The level of urethral nitrite and glutathione was increased too. But the level of urethral lipid peroxide increased in STZ induced diabetic rats was decreased as lowly as normal group by the extract of BF. In conclusion, the extract of BF can restore erectile dysfunction of STZ induced diabetic rats.