Periodontal disease is a change in the supporting tissue ie bone and periodontal ligament around the teeth in a progressively destructive manner that can cause eventual loss. Material that is often used to repair periodontal bone destruction is bone graft. The purpose of this article is to evaluate the viability of BHK 21 fibroblast cell culture to bovine tooth hydroxyapatite with MTT assay method. This research is a laboratory experimental research using post-control group design. The sample's result after using Federer formula is >9, and with a concentration of 30 mg, two concentrations of 10% and 50% were used. The results of the MTT test were then calculated into the percentage of living cells and continued to data analysis. The result is that living cells in the percentage of 10% are 97% and at the percentage of 50% is 94%. Based on the CD50 parameter, the bovine tooth graft material is not toxic because the cell lives above 50%. From the results of the normality test, obtained normally distributed data and the results of different tests obtained the two data are not significantly different. Bovine tooth graft material in 10% and 50% concentration is viable to fibroblast cell culture.