Background Psoriasis as chronic recurrent erythermatous-scaly skin disease affects approximately 2% of the white population; it ranges in severity from mild and steady to severe and life-threatening. Psoriasis pathogenesis is still unknow: it probably depends on genetic factors activated by several different agents (stress, drugs, environment, infections, etc.). Some keratinocyte modifications (increase of mitotic activity, alterated differentiation) and dermo-epidermic inflammatory events are responsible of psoriasic lesions. Objectives The objective of the study is to evaluate the homeopathic treatment efficacy in a multifactorial genetic disease like psoriasis. Generally the suppressive traditional medicine methods generate unsatisfactory results. Materials and Methods 20 patients from both sexes, aged from 20 to 70 years, were considered. They were affected by mild or moderate psoriasis (with reference to the Psoriasis Area and Severity Index - PASI) and without any other dermatologic pathology. Each patient, who had suspended for at least 4 weeks every topic and systemic antipsoriasis therapy, was evaluated with an entry traditional clinical examination (PASI and hematochemical tests of renal, liver and hemopoietic function). Then the patient was introduced in an homeopathic protocol, which included a preliminary examination and further controls after 1,3,6 months.   Results   After 6 months from the treatment star the results showed  the foolowing: clinical remission in two patients (guttate and extensive plaque); remarkable improvement in three patients (palmar keratodermic, extensive plaque); improvement in one patient (scalp, elbow and knee plaques); mild improvement in three patients (palmoplantar, extensive plaque, plaque); stationary in threee patients (in one of these the psoriasis was resolved in some areas and appeared in others); mild worsening in one  patient (scalp, elbow and sacrum plaque); worsening in one patient (extensive plaque); three patients were not evaluable because they were out of the trial after the entry visit and one after the first control; two patients had worsened, but the therapy was incompletely followed. In conclusion, out of 20 patients: 11 improved (from mild improvement to complete remission); 2 showed stationary conditions; 1 worsened and 6 patients were out of the trial.   Conclusions   Our study results confirm the treatment's effectiveness on the individual and not on the disease. Considering the human as a unit made of both "psyche" and "soma", this "natural" therapeutic approach opposes to the traditional suppressive treatment, in that it stimulates and potentiates the "inside" abilities. The homeopathy seems to increase the individual capacity (neuro-psyco-endo-immunology) when it is not suppressed by a pharmacological treatment. As in all the diseases with a genetic substrate and multifactorial agents homeopathy can prevent or remove the different inputs capable to activate the genetic pathway.