Advances which have been made in the field of lipid chemistry and bio chemistry during the last ten years mainly are the results of progress in metho dology. The introduction of isotopic and chromatographic techniques has not only enriched our knowledge of normal lipid metabolism but has also greatly enhanced the understanding of the various lipidoses. This is well illustrated by a comparison of the contents of the present monograph with those of my 1955 review in Handbuch der Inneren Medizin (Springer). In addition to better information about the classic lipid thesaurismoses Nie mann-Pick disease, Gaucher's disease and Tay-Sachs disease, the number of hereditary lipid storage diseases has increased considerably through the recogni tion of new syndromes such as metachromatic leukodystrophy, Fabry's disease, Refsum's disease (heredopathia atactica polyneuritiformis), a-p-lipoproteinemia, and Tangier disease. Conversely, disorders such as Hand-Scholler-Christian disease which has been considered a lipidosis up to 1958 (THANNHAUSER) must now be differentiated from the hereditary disturbances of lipid metabolism. Essential hyperlipemia which at one time seemed to be a well defined entity has now been recognized to consist of a number of subgroups, whose pathogeneses appear to be quite different, and whose classification is by no means definite. Similar problems exist for "essential hypercholesterolemia." Since the knowledge of today is the key for the solutions of tomorrow, we are fortunate that the chapters on lipidoses are supplemented by a comprehensive account of lipid chemistry and biochemistry which has been coordinated by W. STOFFEL.