Histamine is an intriguing compound; the same is true for the several classes of anti-histaminergic compounds. The classical anti-histamines, now known as H -antagonists have 1 been the result of intensive research in the 1950s and 1960s. The new, so-called non-sedating H1-antagonists, which became available in the 1980s, could be d'eveloped mainly due to insights into structural features causing the sedating effects of the older compounds. In the 1970s the H2-receptors became important targets for developing new anti-ulcer agents. The H2-antagonist story is a stimulating example of modern...