Mammalian cells react to microstructured surfaces, but there is little information on the reactions to nanostructured surfaces, and such as have been tested are poorly ordered or random in their structure. We now report that ordered surface arrays (orthogonal or hexagonal) of nanopits in polycaprolactone or polymethylmethacrylate have marked effects in reducing cell adhesion compared with less regular arrays or planar surfaces. The pits had diameters of 35, 75, and 120 nm, respectively, with pitch between the pits of 100, 200, and 300 nm, respectively. The cells appear to be able to distinguish between different symmetries of array. We suggest that interfacial forces may be organized by the nanostructures to affect the cells in the same way as they affect liquid crystal orientations.