The purpose of this study was to conduct a systematic review of the scientific medical literature to identify, appraise, and synthesize the evidence for the health effects of omega-3 fatty acids on asthma. Asthma is a chronic inflammatory disorder of the airways leading to airways hyper-responsiveness and associated symptoms such as wheezing and coughing, and is also typically associated with widespread but variable airflow obstruction that is often reversible either spontaneously or with treatment. The inflammatory process is a complex one, involving a multitude of cell types and activities marking the early and late phase asthmatic responses. There are important issues requiring careful consideration in diagnosing asthma, including the need to distinguish it from transient wheezing disorders in children, especially under the age of 5 years, and also from chronic obstructive pulmonary disorder, especially in older adults who are current or ex-smokers. Various strategies have been developed to manage asthma. Since airway inflammation is multifactorial, involving various cell types and mediators, the drugs used to decrease inflammation may act at several different steps in the inflammatory process. Agents that modify the asthma process, with some influencing inflammation, include: beta-2 adrenergic agonists, corticosteroids, leukotriene modifiers, mast-cell stabilizing agents, and theophylline. Considerable interest in the possible value of omega-3 fatty acid supplementation in asthma was sparked by Horrobin's hypothesis that the low incidence of asthma in Eskimos stems from their consumption of large quantities of oily fish, rich in omega-3 fatty acids. Additional impetus for research came from observations that omega-3 fatty acids' possible protective, or even therapeutic, effect might be afforded by their impact on mediators of inflammation thought to be related to the pathogenesis of asthma.