Purpose: The purpose of this study is to evaluate which FRC-posts were more distinguishable from core. Materials and Methods: Nine extracted single-rooted mandibular premolars with similar lengths (± 0.5 mm) and widths (± 0.5 mm) were endodontically treated and obturated. One specimen which the three roots were embedded in a cold mounting resin was made. 3 specimens were made by this method. Post spaces were prepared for the following post system: FRC Postec® Plus, MACRO-LOCK TM POST ILLUSION TM XRO®, Snowpost®. After three different posts were placed in the roots of a specimen, each three specimens received a direct core build-up: Luxacore® Dual A3, Luxacore® Dual blue, Filtek TM Z350 A1E. Digital images were taken of the post and core with and without air-blowing. We asked to fifty dentists and fifty dental college students which post was more clearly discriminated from the core. Results: In surveys, when core was Luxacore® Dual blue, among three types of posts people more easily discriminated the Snowpost® from core. When core was Luxacore® Dual A3, among three types of posts people similarly more easily discriminated Snowpost® from core. When core was