A rat bone marrow cell culture was used to evaluate the osteogenic potential of amorphous and crystalline thin calcium phosphate (Ca/P) coatings. The coatings were deposited on titanium discs using a radiofrequency magnetron sputter procedure. Amorphous and crystalline plasma spray Ca/P coated and noncoated titanium discs served as reference material. The cellular behavior was analyzed with quantitative (attachment and proliferation rates) and qualitative (scanning electron microscopy) techniques. No significant differences were found in cell attachment and proliferation rates between the various materials. Scanning electron microscopy showed extracellular matrix formation after 18 days of culture on amorphous plasma-sprayed and the two types of magnetron sputtered coatings. Furthermore, no severe degradation of the magnetron sputtered coatings was observed. They even appeared to induce apatite formation. On basis of the results, we conclude that magnetron sputtering appears to be a promising method to manufacture bioactive ceramic coatings.