Polyunsaturated fatty acids (PUFA), omega-3 are essential for normal development and function of the central nervous system. They are an essential structural component of neuronal cell membranes and are a source of biologically active substances, which perform complex functions, and participate in signal transmission within cells. Disorders of lipid metabolism and FFA are observed in the course of many disorders and mental illness, i.e. schizophrenia, bipolar disorder, attention-deficit/hyperactivity disorder, autism. Those disturbances are genetically based and contribute along with other abnormalities to increased vulnerability to particular disorder’s symptoms development. In addition, the diet of most residents of European countries does not provide enough omega-3 PUFAs, are exogenous substances, i.e. not synthesized in sufficient quantities in the human body. Moreover, in the course of many mental disorders an excessive loss of long-chain PUFA through excitotoxicity processes and oxidative stress is observed, which further contributes to depletion of the available pool of PUFAs. In the case of schizophrenia, numerous experimental and clinical studies have led researchers to formulate hypotheses explaining the development of this disease based on the presence of lipid metabolism dysfunctions. The paper presents a review of recent literature and results of the original research conducted by the authors dealing with PUFAs metabolism disturbances in patients with mental disorders listed above.