There have been many earlier reviews of the approach that one might take to the separation and identification of cells from a tissue not previously studied. The use of purified cells in suspension from tumors and from the tissues that are the ancestral precursors of tumors offers a different kind of environment in which to study the effects of polyunsaturated fatty acids and eicosanoids in their interactions with these cells. In the space available in this chapter, we shall present an overview of the methodology in this area and shall refer the reader to other reviews for the more detailed treatment of different aspects of this subject.