Despite the impressive advancements in the treatment of psoriasis over the past two decades, there is still a need for further improvement. As previously shown in the literature, genistein (5,7-dihydroxy-3-(4-hydroxyphenyl)chromen-4-one), naturally occurring plant compound displays multidirectional action, also in relation to alleviating psoriasis symptoms. In this work we focused our attention on genistein impact on expression of genes when treating moderate-to-severe psoriasis patients. Testing the effects of this isoflavone on transcript levels in both skin specimens and peripheral blood cells of four psoriatic subjects, we found that this compound modulated activities of genes coding for anti-psoriatic members and anti-inflammatory mediators of inflammation. It impairs the activity of certain genes which are overexpressed in psoriasis, while stimulating the expression of other transcripts that are repressed in dermatosis.