Background and Design: Psoriasis is a common, chronic, relapsing skin disease, characterized by the formation of typical scaly papules or plaques. The three factors well-recognized as triggering the onset, causing new lesions or inducing a flare in the disease are: stress, skin injury and infection. Various microorganisms are associated with provocation and/or exacerbation of psoriasis. The aim of this study was to investigate the relationship between parvovirus B19 (PVB19) and psoriasis/psoriasis area severity index (PASI).