An in vitro culture of human osteoblastlike cells was established in order to perform toxicity tests with materials interacting with bone in vivo. Different dental materials were tested with osteoblastlike cells and with human gingival fibroblasts. Direct and indirect tests were performed according to the different properties of the materials. It was found that the osteoblastlike cells in test cultures were affected by materials that caused no visible cell damage in the fibroblast cultures. The results indicated that human osteoblastlike cell cultures represent a highly sensitive test system for cell-specific toxicity.