AbstractA method is described for making histological sections of tumor pellets prepared from very small particulate samples of breast cancer originally pulverized for biochemical analysis of estrogen and progesterone receptors. Pulverizing the frozen tumor fractures it into fine particles with remarkably intact microscopic anatomy. This method embeds and concentrates the particles in matrices suitable for preparation of either frozen or permanent histological sections. We have used these tumor pellets and standard immunohistochemical procedures to study multiple biologically and prognostically important markers on single 50 mg samples of breast cancer from a large frozen tumor bank with long-term clinical follow-up. (The J Histotechnol16:117, 1993)