Purpose: Sulforaphane is a naturally-occurring isothiocyanate abundant in broccoli. It has been suggested as a promising antioxidant. In this study, the therapeutic effect of sulforaphane in paraquat intoxication was investigated. Methods: Paraquat was administered via the tail vein, after which sulforaphane or a vehicle (4% DMSO) was administered intraperitoneally 15 minutes after paraquat administration. Histological injury, lipid peroxidation, plasma cytokine (IL-6, IL-10), and nitric oxide were measured. In addition, the effect of sulforaphane on survival in paraquat-intoxication was observed. Results: Regarding histological injury, lipid peroxidation, and plasma cytokine and nitric-oxide response, sulforaphane administration showed no protective effects in paraquat-intoxicated rats. Rather, it increased mortality (log rank p=0.03) and caused lipid peroxidation, as well as plasma cytokine and nitric-oxide production, to be increased. Conclusion: Sulforaphane had no therapeutic effect on paraquat-intoxicated rats; rather, it increased mortality.