Renal protection of s-allyl cysteine (SAC) and s-propyl cysteine (SPC) in diabetic mice against inflammatory injury was examined. Each agent at 0.5 and 1 g/L was added to the drinking water for 10 weeks. SAC or SPC intake significantly reduced the plasma blood urea nitrogen level and increased creatinine clearance (P < 0.05). These treatments significantly lowered the renal level of reactive oxygen species, nitric oxide, interleukin-6, tumor necrosis factor-α, and prostaglandin E(2) in diabetic mice (P < 0.05). Renal mRNA expression of inducible nitric oxide synthase, cyclooxygenase-2, protein kinase C (PKC)-α, PKC-β, and PKC-γ was enhanced in diabetic mice (P < 0.05); however, SAC or SPC treatments dose dependently declined mRNA expression of these factors (P < 0.05). Nuclear factor κB (NF-κB) activity, mRNA expression, and protein production in kidney of diabetic mice were significantly increased (P < 0.05). SAC or SPC intake dose dependently suppressed NF-κB activity, NF-κB p65 mRNA expression, and protein level (P < 0.05). Diabetes also enhanced renal protein expression of mitogen-activated protein kinase (P < 0.05). SAC and SPC, only at a high dose, significantly suppressed protein production of p-p38 and p-ERK1/2 (P < 0.05). Renal mRNA expression and protein generation of peroxisome proliferator-activated receptor (PPAR)-α and PPAR-γ were significantly down-regulated in diabetic mice (P < 0.05), but the intake of SAC or SPC at high dose up-regulated PPAR-α and PPAR-γ (P < 0.05). These findings support that SAC and SPC are potent anti-inflammatory agents against diabetic kidney diseases.