AbstractA key problem in structural studies of fatty acid glycerides is imposed by the sensitivity of shifts between the beta and alpha positions. The analogous aromatic esters, halides and ring structures tend to be more stable. Hence structures reported before 1923, when systematic studies were developed, were nearly all wrong or uncertain. The second major hurdle was to identify and control the position and configuration of the ethylene groups. Then two great leaps forward developed, in parallel, particularly in biological and medical research, when isotopes and micro chromatography became available. Now it is clear that each fatty acid has significant roles to play in normal biological functions and in relation to major problems in health and agriculture. These relationships are particularly fascinating and significant in relation to linoleic acid and the prostaglandins.