Purpose: To systematically review the best supportive care (BSC) literature and to evaluate the ethical and methodologic validity issues by using widely acknowledged criteria. Methods: Two search strings that included both cancer and supportive as terms (with random article type, or review or meta-analysis) explored databases from 1966 to 2008. Citations, abstracts, and papers were reviewed for inclusion criteria, and relevant data were extracted by two independent researchers. Data were validated for accuracy. Ethical and methodologic validity were evaluated by using the criteria derived from the Helsinki Requirements of the WMA; CONSORT statements for the evaluation of reports of randomized, controlled trials; and the universal requirements for ethical clinical research. Results: Forty-three published papers were identified that described 32 studies, 20 of which incorporated the design of treatment plus supportive care (SC) versus SC alone, and 12 of which incorporated the design of treatment versus SC. Most of the studies had poor compliance to critical Helsinki requirements, to methodologic precautions derived from the CONSORT statement for studies involving a nonpharmacologic arm, and to four of seven universal requirements for ethical clinical research. Conclusion: Lack of rigor in BSC studies has contributed to a generation of research with widespread ethical and methodologic shortcomings. Ad hoc SC and lack of standardization of SC delivery may be sources of systematic bias or error in BSC trials. Rectifying these shortcomings in future studies demands greater vigilance toward these issues by researchers, institutional review boards, editors, and peer reviewers. Given the prevalence of overlooked problems that are later identified, currently open BSC studies should be reevaluated by institutional review boards and researchers to check for ethical and methodologic validity, and identified shortcomings should be addressed. �� 2009 by American Society of Clinical Oncology.