Primary stability and postponement of loading of dental implants for approximately 3 to 6 months have been considered for years the "conditio sine qua non" to allow osseointegration of dental implants. However, in recent years, an increasing number of publications on immediate and early loading of dental implants in completely edentulous patients have appeared in the literature, and high survival rates were generally reported. Nevertheless, much controversy still exists over the reliability of the reported data, frequently because the publications are of insufficient methodologic quality (insufficient follow-up, inadequate sample size, absence of randomization, lack of well-defined exclusion and inclusion criteria, lack of well-defined success criteria, etc). The objective of this study was to review the literature to evaluate the reliability of early and immediate loading of implants placed in the edentulous mandible and maxilla and rehabilitated either with implant-supported overdentures or with implant-supported fixed prostheses.