In this study, human umbilical vein endothelial cells were seeded for 3 and 24 h on polystyrene (PS), tissue culture polystyrene (TCPS) and polystyrene modified by oxygen plasma treatment (PtPS) in order to investigate their detachment behaviour during exposure to fluid shear. All three materials have smooth surfaces at the submicron level. Equilibrium water contact angles were higher on PS (88°) than on TCPS (78°) and PtPS (79°). Furthermore, contact angle hysteresis, i.e. the difference between advancing and receding angles, was much larger on TCPS (39°) and PtPS (41°) than on PS (14°), indicating either a large surface heterogeneity or a possible reorientation of functional groups on TCPS and PtPS. X-ray photoelectron spectroscopy data revealed that both TCPS and PtPS had oxygen incorporated at their surfaces (18.6% and 9.9%, respectively), whereas only TCPS had a small amount of nitrogen (0.9%) at its surface. Cells seeded on these materials were exposed to various shear stresses in the range 88–352 dyn cm −2 in order to gain more insight into the influence of the specific physico-chemical surface properties of these polystyrene surfaces on cell retention, cell morphology and migration. The retention of cells having adhered during 24 h on TCPS and PtPS was not different from the retention of cells having adhered during 3 h, but retention on TCPS and PtPS was higher than on PS. At shear stresses of 88 and 176 dyn cm −2, however, differences in the morphology of cells adhered to TCPS during 3 and 24 h were observed, indicating that between 3 and 24 h changes in cell-substratum interactions occurred. Migration on TCPS and PtPS was accompanied by the presence of fibrillike structures left behind on the surface. Summarizing, this study shows that cell retention is higher on modified polystyrenes than on polystyrene, the only major difference between the polystyrenes being the higher contact angle hysteresis and oxygen content of the modified polystyrene surfaces.