This review presents, from the author's viewpoint, avenues of histamine research likely to produce new information. One potentially useful approach may be to attempt to relate histamine's function to its occurrence in different body tissues such as the pituitary and hypothalamus, the gastrointestinal mucosa, and the bone marrow and white blood cells. Prospects also seem bright for quantitative studies of histamine metabolites in blood and urine and possible changes in the relative amounts of these metabolites in a variety of diseases.