The ability to grow cells in monolayer culture has afforded investigators the opportunity to study many aspects of cancer cell biology under carefully controlled conditions. Nonetheless, an important factor that has often been overlooked is that cells in this configuration undergo a loss of structural integrity that may significantly alter their functional properties. Three-dimensional histoculture represents a useful alternative approach to monolayer culture because it preserves the native architecture of cells while still allowing ease of experimental manipulation. This review discusses the origins of three-dimensional cultures, the potential application of these cultures to assays of tumor cell metastasis and drug sensitivity, and the evidence from gene expression studies that these cultures may be more realistic tumor models than cell monolayers.