Polyunsaturatted fatty acids (omega acids), first of all of groups omega-3 and omega-6, have heterogeneous physiological roles. Some of those roles are very important for the functions of central nervous system. Omega-3 acids have neuroprotective and antiinflammatory effects, they constitute the precursors of some neurotransmitters. Some of them have antioxidant effects. On the other hand, omega-6 acids have proinflamattory properties. Lack of omega-3 acids could promote different pathological changes, as well as the change of omega-3:omega-6 ratio. Docohexaenoic acid is very important for the working of central nervous system. Omega acids are important for the maturation of central nervous system, and their deficit could results or participates on the genesis of developmental disorders, hyperkinetic syndrome, and autism. The functions of those matters are investigated in Alzheimer´s disease and other dementias, in schizophrenia, depressions, attention deficit and hyperkinetic disorder and other psychic disorders. Omega fatty acids are an important nutritive supplement of therapy of those disorders, and they have also protective effects.

        Key words: Alzheimer´s disease, dementia, depression, eicosanoids, omega-3 and omega-6 polyunsaturatted fatty acids, schizophrenia.