Two cases of Gaucher's disease (Types I and III) are described with a substantial part of the storage cell population in several organs (liver, adrenal cortex) intensively vacuolized and transformed into non-specific foam cells. The transformation process encompassed massive three-dimensional distension of the lysosomal system filled with typical lipid tubules as well as severe reduction of the intervening cytoplasm and decrease or disappearance of histochemically detectable enzyme activities, high in typical Gaucher cell (GC). Such an extensive GC foamy transformation may cause diagnostic embarrassment in microscopic interpretation especially of liver biopsies.