© 2014 by American Society of Clinical Oncology. Purpose: Clinical practice guidelines (CPGs) and consensus statements (CSs) are used to apply evidence-based medicine or expert recommendations to clinical practice. Here we explore author financia conflicts of interest (FCOIs), sources of guideline funding, and their relationship with endorsement of specific drugs.Methods: An electronic search of MEDLINE was conducted to identify CPGs and CSs for common solid cancers published between January 2003 and October 2013. The search was restricted to articles evaluating systemic therapy. We extracted data on self-reported author FCOIs, funding sources, use of manuscript writers, and endorsement of specific drugs in the abstract of the article.Results: Of 142 articles evaluated, 64% were CPGs, and 36% were CSs. The proportion of articles reporting FCOIs improved from 11% in 2003 to 93% in 2013 (Pfor trend <.001). Only 45% of articles explicitly reported funding sources. Of these, 65% disclosed partial or full industry sponsorship. Use of manuscript writers was declared in 13%, but many articles did not explicitly report the role of authors in the writing of the manuscript. Endorsement of specific drugs was significantly associated with author FCOIs (odds ratio [OR], 7.29; P =.001), but not with industry funding (OR, 0.95; P =.37).Conclusion: Reporting of FCOIs in CPGs and CSs has improved over time. Despite prevalent funding of guideline development by industry, such funding is not associated with endorsement of specific drugs. Author FCOIs are prevalent, and endorsement of a specific drug seems to be more common when authors have FCOIs with the pharmaceutical company marketing that drug.