Under many circumstances, macrophages accumulate lipids (possibly in combination with other materials) in the form of micelles that by their rigidity and size impart an irregular, angulate shape to the lysosomes in which they are stored. When macrophages contain large numbers of these angulate lysosomes, they have a characteristic light microscopic appearance and are often designated Gaucher cells or Gaucher-like cells. In most instances, however, the angulate lysosomes are small in number or size and are not easily recognized by light microscopy. A search of the literature and our own files revealed angulate lysosomes in a considerable number of conditions in which they have not previously been observed or recognized. In most conditions, the evidence indicates that the material stored is derived from phagocytosed cells that are incompletely digested, either because they are simply too numerous to be handled by the macrophage or due to a primary metabolic deficiency, or both. In contrast to what has been assumed, angulate lysosomes not only arise in situations in which blood cells are phagocytosed, but also when various types of degenerating tumor cells, remnants of myelin sheaths, or bacteria accumulate inside macrophages. In yet other conditions, the origin of the lysosomal contents remains to be elucidated.