Aim: The aim of this systematic review was to evaluate and synthesise the existing evidence on the effect of the prosthetic implant abutment design and fabrication process on mechanical, biological and aesthetic clinical outcomes. Materials and methods: Two electronic databases (PubMed and Embase) were searched in August 2016 to identify clinical studies evaluating the clinical outcomes of CAD/CAM abutments. The studies were screened and two reviewers used the full text to extract data independently. A qualitative synthesis was performed on the extracted data and summary tables were prepared. Due to heterogeneity in the studies included, no meta-analysis was performed. Results: Twenty-four studies were included in this review. Of these, 13 studies focused solely on CAD/CAM abutment and did not include a control group, or a comparison with conventional implant abutments. Eleven studies compared clinical outcomes of CAD/CAM abutments with conventional abutments. There were only three clinical trials and the majority of the studies were observational or case series studies. The most commonly reported clinical outcomes measured were soft tissue volume and aesthetic scores, survival and success rates, and marginal bone levels. Conclusion: The results of the review demonstrate that CAD/CAM abutments had overall good survival and success rates and that they provide comparable, if not better, clinical outcomes when compared with conventional abutments. However, existing evidence is weak as few randomised control trials were conducted and follow-up periods were, in general, short.