Purpose: In the present prospective study, four different post-and-core systems were evaluated over a period of up to 10 years. Materials and Methods: Fifty endodontically treated teeth in 31 patients were randomized to one of four groups for post-and-core placement: Group 1 received conventional tapered cast posts and cores (n = 14); group 2 received ParaPost system prefabricated gold posts with cast cores (n = 13); group 3 received ParaPost system cast posts and cores (n = 13); and group 4 received Radix-Anchor posts (n = 10). Clinical and radiologic evaluations were made. Results: One post and core in group 2 was functioning well 58 months after placement when the patient died. No posts and cores in groups 1 or 2 had been lost or had any complications, one in group 3 had been lost because of a root fracture after 108 months, and two in group 4 had been lost after 54 and 88 months, respectively, because of loss of retention. The final treatment result for 46 of the 49 remaining posts (30 patients) was successful. The overall failure rate was 6%. There were no statistically significant differences between the four groups. Conclusion: If recommended procedures are strictly followed, posts and cores can serve as abutments for fixed single crowns with satisfactory long-term results. Int J Prosthodont 2003;16:249–254.