We report on the synthesis of thin composites of diamond-like carbon (DLC) and nanocrystalline ZrO 2 deposited using pulsed direct current plasma-enhanced chemical vapor deposition at low temperatures (<120 °C). Films containing up to 21 at.% Zr were prepared (hydrogen was not included in the calculation) and their structural and surface properties were determined using a number of spectroscopic methods and contact angle measurements. Bone cell adhesion to the films was studied using a 3 day cell culture with osteoblasts. These nanocomposites (DLC-ZrO 2 ) consist of tetragonal ZrO 2 nanocrystals with an average size of 2-5 nm embedded in an amorphous matrix consisting predominantly of DLC. The surface water contact angle of the films increased from $60°to 80°as the Zr content increased from 0 to 21 at.%. The cell culture study revealed that although the cell counts were not significantly different, the morphology of the osteoblasts growing on the DLC-ZrO 2 nanocomposites was markedly different from that of cells growing on DLC alone. Cells growing on the DLC-ZrO 2 surfaces were less spread out and had a smaller cell area in comparison with those growing on DLC surfaces. In some areas on the DLC-ZrO 2 surfaces, large numbers of cells appeared to coalesce. It is postulated that the difference in cell morphology between osteoblasts on DLC-ZrO 2 surfaces and DLC surfaces is related to the presence of very small tetragonal nanocrystals of ZrO 2 in the composite film.