Purpose: To test the null hypothesis that there is no difference in failure rates between various root-formed osseointegrated dental implant systems after 5 years of loading. Materials and Methods: A search was conducted for all randomized controlled clinical trials (RCTs) comparing different implant systems with a follow-up of 5 years. The Cochrane Oral Health Group's Trials Register, CENTRAL, MEDLINE, and EMBASE were searched. Several dental journals were also searched by hand. Written contacts were established with authors of the identified RCTs and with more than 55 oral implant manufacturers and personal contacts to identify unpublished RCTs. No language restriction was applied. The last electronic search was conducted on February 1, 2005. Screening of eligible studies, quality assessment, and data extraction were conducted in duplicate. Results were expressed as random effect models using weighted mean differences for continuous outcomes and relative risk for dichotomous outcomes with 95% confidence intervals. Results: Ten RCTs were identified. Four of these RCTs, reporting results from a total of 204 patients, were considered suitable for inclusion. Six different implant types were compared. On a per-patient rather than a per-implant basis, there were no statistically significant differences, with the exception of more marginal bone loss around early loaded Southern implants when compared to early loaded Steri-Oss implants (mean difference -0.35 mm; 95% CI -0.70 to -0.01). However, the difference disappeared in the meta-analysis. Discussion and Conclusions: There were no clinical differences among implant systems. However, these findings are based on only 4 RCTs with few participants. More RCTs should be conducted with larger patient samples.