We sought to establish a causal relationship between oxidative stress and porphyria in patients and carriers. We reported changes in urinary porphyrin concentrations related to 8-hydroxy-2′-deoxyguanosine. Methods: We measured urinary 8-hydroxy-2′-deoxyguanosine concentration in porphyria patients and carriers with multifactorial inheritance as a possible marker of attack. The porphyria types included 10 patients with porphyria cutanea tarda, 5 with variegate porphyria, 8 with hereditary coproporphyria, 7 with congenital erythropoietic porphyria, 5 with erythropoietic protoporphyria, 5 with acute intermittent porphyria, 7 erythropoietic protoporphyria carriers, and 7 acute intermittent porphyria carriers. Results: Urinary porphyrin concentrations in these patients were significantly higher than those in healthy subjects ( p <0.001). Urinary 8-hydroxy-2′-deoxyguanosine concentrations were significantly high in dermatopathy porphyria types namely porphyria cutanea tarda ( p <0.001), variegate porphyria ( p <0.05), hereditary coproporphyria ( p <0.05), congenital erythropoietic phyria ( p <0.05), and erythropoietic protoporphyria ( p <0.001). Conclusion: These results reveal that urinary 8-hydroxy-2′-deoxyguanosine concentration in cutis porphyria types is a good predictor of attack and abatement.