To elucidate the influence of microtextures on bone cell performance, primary adult rat bone marrow cells (RBMC) and osteoblastic MC3T3-E1 cells were cultured on tissue culture pretreated plates to which grooves at different density were applied. RBMC cells were found to be significantly affected by grooves in the substratum in contrast to osteoblastic MC3T3-E1 cells, taking culture morphology, total cell number, cell mass, and cell activity (MTT-dehydrogenase), parameter for differentiation of osteoblast progenitor cells into (pre-)osteoblasts (alkalinephosphatase activity, ALP) and tartrate-resistant acid phosphatase (TRAP) activity as indices. TRAP is located in lysosomes and secretory granules mainly although not solely in osteoclasts. By applying grooves to and/or by chemical treatment of unpretreated pure polysterene plates it could be concluded that the effects on RBMC cells were evoked not only by the presence of grooves but also by the surface chemistry of the grooved and ungrooved surface areas.