Many different materials have been used in prosthetic treatment throughout dentistry's long history. Currently, in the development of new materials, biological properties have become markedly important, along with physical and mechanical properties. Biocompatibility has been described as the ability of a material to perform with an appropriate host response in a specific application.Appropriate host response means no adverse reaction of a living system to the presence of such a material. An adverse reaction may be due to the toxicity of a dental material. Therefore toxicity may be regarded as one reason for non biocompatibility of a dental material. Biocompatibility is an important feature of any material designed for use within the body. Biocompatibility is the result of interactions between the material, patient and function, and is an ongoing process. Materials' biocompatibility is evaluated with in vitro tests, animal tests and usage tests. In the evaluation of the biologic effects of dental materials, in vitro testing methods using cell cultures have become more common, and several cell culture methods have been developed to assess the cytotoxicity of dental materials. In vitro tests are simpler than animal and usage tests. These tests, performed under repeatable and controllable conditions and presenting comparable results, give information about a material's first usage. Cell or tissue cultures play an important role because they allow a maximum standardization. Future efforts may be directed toward development of materials biocompability for safety application. This article presents a review of the literature about evaluation methods of biocompatibility of dental materials.