Psoriasis is an immune mediated chronic inflammatory human disease of unknown etiology and characterized by epidermal hyperplasia and inappropriate immune activation, which affects the skin and joints as well. Increased concentrations of free arachidonic acid (AA) and its pro-inflammatory metabolites have been observed in psoriatic lesions. Replacement of arachidonic acid by alternative precursor polyunsaturated fatty acids (PUFA), might be a therapeutic option in psoriasis. Fish oil contains n-3 polyunsaturated fatty acids, mainly eicosapentaenoic (EPA), and docosahexaenoic acids (DHA), reduces symptoms in many inflammatory skin diseases. The mechanism of action of fish oil in the treatment of psoriasis is widely based on the alteration of epidermal and blood cell membrane lipid composition. In conclusion, n-3-fatty acid administration causes reduction of psoriasis, which may be related to changes in inflammatory eicosanoid generation. oral administration of fish oil n-3 polyunsaturated fatty acids had positive effects. However, further studies are warranted to answer many intriguing questions, for instance, the ideal quantity of fish oil to be utilized, the effect on different forms and severity of psoriasis . we conducted a systematic review of all randomized controlled trials and observational studies that determined the effects of n-3 PUFAs on outcomes in patients with psoriasis compared with control treatment.