Objective: Here we investigate the effects of the endogenous prostaglandin D₂ metabolite 15-deoxy-Δ^12,14-prostaglandin J₂, on the renal dysfunction and injury caused by ischemia/reperfusion of the kidney. Methods: Male Wistar rats, subjected to bilateral renal ischemia for 45 min followed by reperfusion for up to 48 h, were administered 15-deoxy-Δ^12,14-prostaglandin J₂ (1 mg/kg, intravenously) 5 min prior to and again after 3 or 12 h reperfusion. Results: 15-deoxy-Δ^12,14-prostaglandin J₂ significantly reduced (i) renal and tubular dysfunction (serum urea and creatinine levels, creatinine clearance, fractional excretion of Na⁺ (FE_Na)), (ii) tubular and reperfusion-injury (urinary N-acetyl-β-d-glucosaminidase, aspartate aminotransferase (ASP) and γ-glutamyltransferase (γ-GT)) and (iii) histological evidence of renal injury. 15-deoxy-Δ^12,14-prostaglandin J₂ also improved renal function (plasma creatinine levels) and reduced the histological signs of renal injury (after 48 h reperfusion). Administration of 15-deoxy-Δ^12,14-prostaglandin J₂ markedly reduced the expression of inducible nitric oxide synthase (iNOS) and intercellular adhesion molecule-1 during reperfusion (determined using immunohistochemistry). Immunohistochemical analysis of p65 translocation and Western blot analysis of IκB-α degradation revealed that 15-deoxy-Δ^12,14-prostaglandin J₂ inhibited the activation of nuclear factor (NF)-κB in renal cells. Subsequently, 15d-PGJ₂ was able to significantly reduce nitric oxide production during renal ischemia/reperfusion and by primary cultures of rat proximal tubular (PT) cells incubated with interferon-γ and bacterial lipopolysaccharide (LPS) in combination. Conclusions: We demonstrate here, for the first time, that 15-deoxy-Δ^12,14-prostaglandin J₂ significantly reduces renal ischemia/reperfusion-injury via reduction of pro-inflammatory gene expression during reperfusion subsequent to the inhibition of the activation of NF-κB.