This report is one of several reports focusing on the role of omega-3 fatty acids in the prevention or treatment of various diseases. This report focuses on the effects of omega-3 fatty acids on immune-mediated diseases, bone metabolism, and gastrointestinal/renal diseases. Over the past 40 years, an increasing number of physiological functions have been attributed to omega-3 fatty acids, including movement of calcium and other substances into and out of cells, relaxation and contraction of muscles, inhibition and promotion of clotting, regulation of secretion of substances that include digestive enzymes and hormones, control of fertility, cell division, and growth.1 In addition, omega-3 fatty acids may play an important role in brain development and function. Some evidence has suggested that omega-3 fatty acids in the diet may protect against heart attack and stroke, as well as certain inflammatory diseases like arthritis, lupus, and asthma. The major dietary sources of omega- 3 fatty acids in the U.S. population are fish, fish oil, vegetable oils (principally canola and soybean), walnuts, wheat germ, and some dietary supplements. The following conditions were addressed: Rheumatoid arthritis, systemic lupus erythematosis (SLE), and bone density/osteoporosis; Renal disease and diabetes; Gastrointestinal diseases. The TEPs advised us on refining the preliminary questions posed to us by AHRQ, determining the proper inclusion/exclusion criteria for the study and the populations of interest, establishing the proper outcomes measures, and conducting the appropriate analyses.