© 2016 Elsevier Inc. Objective To review the quality of clinical practice guidelines (CPGs) from a wide range of health care topics and report any changes seen since 1992. Study Design and Setting A literature search in MEDLINE, EMBASE, Web of Science Core Collection, and BIOSIS was conducted in London, Ontario, Canada. Publications were screened to identify those assessing the quality of CPGs using the Appraisal of Guidelines, Research and Evaluation (AGREE) II instrument. Data were gathered regarding year of publication, institution type, health topic, country of origin, domain scores, and final recommendation. Results Twenty-five studies met the inclusion criteria. AGREE II scores from 415 individual CPGs published between 1992 and 2014 were obtained. Domain scores increased significantly over time, and the proportion of guidelines being recommended based on AGREE II assessment was significantly greater after 2010. Domain scores in Applicability and Editorial independence had no significant effect on a CPG's final recommendation, whereas other domains had a significant effect. Finally, international development groups produced CPGs with significantly higher scores. Conclusion This review found a steady improvement in CPG quality over time. This is particularly evident in guidelines published after 2010. However, certain domains that are integral to the methodological quality of CPGs remain unsatisfactorily low.