The health benefits of dietary omega-3 fatty acids have been investigated in a variety of conditions but there have been few studies of their effects in human respiratory diseases. Although many of the physiological changes associated with omega-3 polyunsaturate ingestion have been attributed to alterations in endogenous eicosanoid production, effects on blood rheology, host-microbial interactions and lung surfactant production have also been described. In reviewing the literature, there is little evidence that these polyunsaturates have beneficial effects in allergic disorders, but they may have potential as modulators of respiratory diseases involving chronic inflammatory and infectious processes or impaired pulmonary blood flow. Further work on the effects of omega-3 fatty acids in several chronic pulmonary syndromes, for which there are currently no effective therapies, appears to be warranted.