Introduction: Tattooing has been extensively discussed in the literature in the context of hygiene and infectious diseases. On the other hand, pathophysiological effects of tattoo inks in the human body are yet to be elucidated. Oxidative stress is considered to be the most important mediator of potential adverse effects of tattooing, however at the moment there is no experimental evidence for tattoo ink-related oxidative stress in the human body. The aim of this study was to examine the effect of a blue tattoo on skin redox regulatory network (RRN) parameters in a single human subject. Materials and Methods: A blue tattoo on my left forearm was used in the research. Tattooed skin surface oxidation-reduction potential (ORP) experiment was done by a PH60F flat probe. Capillary blood from the tattoo and the control area was extracted and analyzed with I₂/KI-stabilized microORP, nitrocellulose redox permanganometry (NRP), carbonato-cobaltate (III) formation-derived H₂O₂ dissociation rate assay, 1,2,3-Trihydroxybenzene autoxidation assay, thiobarbituric reactive substances (TBARS) assay and 5,5,’-dithio-bis-(2-nitrobenzoic acid) (DTNB)-based determination of free thiol content in low molecular weight and protein precipitate fraction. Results: Surface ORP analysis revealed a greater antioxidant capacity of tattooed skin in comparison with the control (CTR). Capillary blood analysis confirmed slightly greater reductive capacity in the tattoo sample both by microORP (-4.33mV vs CTR) and NRP (+1.1%). Hydrogen peroxide dissociation rate (+11.8%), superoxide dismutase activity (+0.7%), and protein sulfhydryl content (+8.5%) were all increased, and lipid peroxidation (-15%) and low molecular weight thiols (-2.8%) were reduced in a tattoo sample in comparison with the CTR. Conclusion: In this N-of-1 study RRN of tattooed skin was shifted towards a more reductive state with most of the parameters indicating reduced levels of oxidative stress in comparison with nontattooed skin. Local antioxidant effect of copper(II) phthalocyanine provides one possible explanation of the observed effects.