Dietary supplementation omega-3 polyunsaturated fatty acids may inhibit (at least partially) three pathways of the synthesis of lipid mediators of inflammation: the platelet-activating factor synthesis pathway, the cyclooxygenase pathway, and the 5-lipoxygenase pathway. In addition, selected cellular functions of polymorphonuclear neutrophils may be modulated by dietary fish oil. The exact mechanism of the effects of dietary supplementation with omega-3 poly-unsaturated fatty acids on these pathways is not completely elucidated; it is quite probable that the effects will vary with the duration, dose, and composition of the omega-3 polyunsaturated fatty acid preparation, with background medical therapy, and the presence of and degree of activity of the underlying inflammatory disease state.