Purpose: This study determined the radiopacity of a group of nonmetallic posts. Materials and Methods: Four specimens were cut from 7 posts, and tooth sections were cut from extracted teeth. Radiographic images of all specimens along with an aluminum step wedge were obtained on occlusal films. Optical density readings for each specimen image were determined with a transmission densitometer. Radiopacity values were subsequently calculated as equivalents of aluminum thickness. Results: Analysis of variance revealed significant differences in radiopacity values among the posts (P .001). One nonmetallic post that was made of zirconium had a radiopacity value significantly greater than that of enamel. Another, made of glass fibers, acrylic resin, and fillers, had a radiopacity that was greater than that of dentin but smaller than that of enamel. The remaining 3 nonmetallic posts had radiopacity values lower than dentin. Conclusion: The 3 posts with radiopacity that was lower than dentin cannot be considered sufficiently radiopaque.