Zinc is an essential trace element required for bone remodeling process,but its role in such process remains to be elucidated.In this study,zinc-substituted HA coatings have been deposited using a liquid precursor plasma spraying(LPPS)process at two different concentrations(1,2wt.%).The effect of zinc substitution on osteoblastic and osteoclastic differentiation has been studied in-vitro through co-cultures of rat bone marrow stromal cells and osteoclast-like-cell precursor RAW 264.7 cell.