The current study investigated the effect of upregulation of heme oxygenase 1 (HO-1) by cobalt protoporphyrin (CoPP) on renal dysfunctions in renal ischemia/reperfusion (I/R) injury and its underlying mechanisms. 72 male Sprague Dawley rats were divided into 4 groups: sham group, ischemic group (left 45-min renal ischemia), CoPP-before group (as ischemic group with CoPP 20 mg/ kg 30 min before ischemia) and CoPP-after group (as ischemic group with CoPP 20 mg/kg 20 min after ischemia). Serum creatinine, urea and TGF-β1 and markers of redox state (MDA, SOD, GSH and CAT), nitric oxide (NO), TGF-β1 and HO-1 in kidney tissues were measured. Serum creatinine and urea levels were significantly increased in ischemic group and attenuated in CoPP-treated groups (p < 0.05). Also, markers of redox state showed significant deteriorations in ischemic group which were improved significantly in CoPP-treated groups (p < 0.05). HO-1 expression in kidney tissues showed significant increase in ischemic group and showed more significant increase in CoPP-treated groups (p < 0.05). Moreover, serum and renal TGF-β1 levels were significantly increased in ischemic group and attenuated in CoPP-treated groups (p < 0.05). We concluded that up-regulation of HO-1 by CoPP treatment before and after renal I/R injury improved the kidney function and morphology and this might be due to impairment of oxidative stress and inflammatory cytokines in kidney tissues.