This paper deals with the possible impacts of long-chain polyunsaturated fatty acids (PUFA) on human health, primarily in terms of inflammatory responses, the function of T-cells, cytokine production and on membrane fluidity and cell mortality. Low intake of fish oil (5%), in contrast to the high intake (25%) has positive effects on inflammatory human diseases. Supplementation of 18 g/day/6 weeks decreased the proliferation of T-cells associated with a reduction in the secretion of interleukin-2, phytohemagglutinin-stimulated. Omega-3 fatty acids either inhibit or have no effect on the immune response. Large concentrations of eicosapentaenoic and docosahexaenoic acid inhibit the function of neutrophils and monocytes, depending on the amount of vitamin E consumed, and also reduce the pro-inflammatory cytokine function. PUFA fatty acids increase the fluidity of the membrane, resulting in increased cell death rate. omega-6 fatty acids are more influential in that area then omega-3 fatty acids (an exception is linoleic acid, LNA).