We conducted a study to evaluate the quality of guidelines for squamous cell carcinoma of the head and neck (SCCHN) with the exception of nasopharyngeal cancer. Electronic searches were conducted of the U.S. National Guideline Clearinghouse, the Canadian Medical Association Infobase, the Guidelines International Network, the Scottish Intercollegiate Guidelines Network, the China Biology Medicine disc, PubMed, and Embase. Two independent reviewers assessed the eligible guidelines using the Appraisal of Guidelines for Research and Evaluation II (AGREE II) instrument. The degree of agreement among these sources was evaluated by using the intraclass correlation coefficient (ICC). A total of 514 articles were found to be clinical-guideline-related, and 49 guidelines were included in our analysis. Scores were assigned for each of the AGREE II domains: scope and purpose (mean: 71.63% ± 2.80; median: 75%; ICC: 0.76), stakeholder involvement (mean: 43.37% ± 2.96; median: 50%; ICC: 0.93), rigor of development (mean: 45.63% ± 3.84; median: 42%; ICC: 0.83), clarity of presentation (mean: 68.08% ± 2.53; median: 72%; ICC: 0.85), applicability (mean: 32.41% ± 3.03; median: 29%; ICC: 0.92), and editorial independence (mean: 42.55% ± 4.57; median: 42%; ICC: 0.95). We considered a domain score of greater than 60% to represent an acceptable level of quality. We conclude that, overall, the quality of SCCHN guidelines is moderate in relation to international averages. Greater efforts are needed to provide high-quality guidelines that serve as a useful and reliable tool for clinical decision making in this field.