Peptidylarginine deiminase (PAD, EC 3.5.3.15) enzyme catalyzes the conversion of arginine residues to citrulline residues in the presence of calcium ion, which is an elaborate post-translational modification on the target protein. Recently, five isoforms have been identified in mammals. Among them, three isoforms (type I, II, III) are expressed in the human epidermis, and involved in several skin physiological and pathological processes. In the past few years, several researches concerning the transcriptional regulation of three human PADI type genes (PADI1, PADI2 and PADI3) in the epidermis have been carried out. In this review, we describe an overview of the current outcomes about these studies with their significance. It is anticipated that these investigations will provide novel therapeutic and prophylactic targets for future approaches to the treatment or prevention of severe psoriasis and bullous congenital ichthyosiform erythroderma.