Interactions during cell adhesion to external surfaces may reach the level of discrimination of molecular chirality. Cultured epithelial cells interact differently with the {011} faces of the (R,R) and (S,S) calcium tartrate tetrahydrate crystals. In a modified version of the classical Pasteur experiment, the enantiomorphous crystals were sorted out from a 1:1 mixture by the selective adhesion of cells to the (R,R) crystals. This stereospecificity results from molecular recognition between chiral components on the cell surface and the structured crystal surface. Crystals may allow experimental differentiation between distinct stages in cell substrate contacts, providing mechanistic information not readily attainable on conventional heterogeneous surfaces.