Eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), found in oily fish and fish oil supplements, have anti-inflammatory properties. These fatty acids inhibit various aspects of inflammation, including leukocyte chemotaxis, adhesion molecule expression, and leucocyte-endothelial interactions. They also reduce the production of inflammatory cytokines and T cell reactivity. Mechanisms include altering cell membrane phospholipid fatty acid composition, disrupting lipid rafts, inhibiting nuclear factor kappa B activation, and activating peroxisome proliferator-activated receptor γ. Clinical trials suggest that EPA and DHA may benefit patients with rheumatoid arthritis, but the evidence for their efficacy in inflammatory bowel disease and asthma is less clear. The anti-inflammatory effects of marine n-3 polyunsaturated fatty acids are likely to be more pharmacological than nutritional, requiring high doses to achieve significant results.Eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), found in oily fish and fish oil supplements, have anti-inflammatory properties. These fatty acids inhibit various aspects of inflammation, including leukocyte chemotaxis, adhesion molecule expression, and leucocyte-endothelial interactions. They also reduce the production of inflammatory cytokines and T cell reactivity. Mechanisms include altering cell membrane phospholipid fatty acid composition, disrupting lipid rafts, inhibiting nuclear factor kappa B activation, and activating peroxisome proliferator-activated receptor γ. Clinical trials suggest that EPA and DHA may benefit patients with rheumatoid arthritis, but the evidence for their efficacy in inflammatory bowel disease and asthma is less clear. The anti-inflammatory effects of marine n-3 polyunsaturated fatty acids are likely to be more pharmacological than nutritional, requiring high doses to achieve significant results.