Inflammation plays an important role in the pathogenesis of secondary damage after spinal cord injury (SCI). The present study explored the effect of sulforaphane (SFN), a potent anti-inflammatory extract of cruciferous vegetables, on the expression of two inflammatory mediators, metalloproteinase (MMP)-9 and TNF-α, in a murine model of SCI. Murine spinal cord injury was induced by the application of vascular clips (force of 10 g) to the dura after a three-level T8-T10 laminectomy. The wet/dry weight ratio was used to reflect the percentage of water content of impaired spinal cord tissue at 48 hr after SCI. The mRNA levels of MMP-9 were determined using the reverse-transcriptase polymerase chain reaction (RT-PCR), and protein levels of TNF-α and MMP-9 were detected by enzyme-linked immunosorbent assays (ELISA) at 24 hr after SCI. Gelatin zymography was used to determine MMP-9 activity of spinal cord tissue at 24 hr after SCI. Mice treated with SFN at 1 hr after SCI had lower expression and activity of MMP-9 compared to mice with SCI. The decrease of MMP-9 in mice treated with SFN was associated with decreased levels of spinal cord water content and TNF-α. In summary, suforaphane decreases MMP-9 and TNF-α expression and vascular permeability changes following spinal cord injury in mice.