Objectives: To evaluate the efficacy of 1) immediate (within 1 week), early (between 1 week to 2 months), and conventional (after 2 months) loading of osseointegrated implants, and of 2) immediate occlusal versus non-occlusal loading during the bone healing phase. Data sources: The Cochrane Oral Health Group's Trials Register, CENTRAL, MEDLINE and EMBASE were searched and several journals were handsearched with no language restriction up to June 2008. Review methods: All randomised controlled trials (RCTs) of osseointegrated dental implants, having a follow up of 4 months to 1 year, comparing the same implant type immediately, early and conventionally loaded or occlusally and non-occlusally loaded were eligible. Screening of studies, quality assessment and data extraction were conducted in duplicate. Outcome measures were: prosthesis and implant failures and radiographic marginal bone level changes. Results: Thirty RCTs were identified and 22 trials including 976 patients in total were included. Twelve trials compared immediate versus conventional loading, three early versus conventional loading, six immediate versus early loading, and one occlusally versus non-occlusally loaded implants. On a patient, rather than per implant basis, there were no statistically significant differences for any of the meta-analyses. Conclusions: It is possible to successfully load dental implants immediately or early after their placement in selected patients, though not all clinicians may achieve optimal results. It is unclear whether it is beneficial to avoid occlusal contacts during the osseointegration phase. Trends suggest that immediately loaded implants fail more often than those conventionally loaded, but less commonly than those early loaded. If a clinician wishes to load early the implants, it might be wiser to load them immediately (within one week) than waiting for 1 to 2 months. A high degree of primary implant stability (high value of insertion torque) seems to be one of the prerequisites for a successful immediate/early loading procedure. Keywords: dental implants, early loading, immediate loading, randomised controlled clinical trial, systematic review