Background While reporting of individual conflicts of interest is formalised, it is unclear to what extent the funding of clinical practice guidelines (CPGs) is formally reported. The aim of this study is to explore the accuracy and comprehensiveness of reporting on funding in German CPGs. Methods We searched for CPGs in the registry of the Association of the Scientific Medical Societies in Germany in July 2020. Information on guideline funding was categorised by two reviewers independently and discrepancies were clarified by (...) discussion with a third reviewer. Accuracy and comprehensiveness of reporting on funding was assessed using the German Instrument for Methodological Guideline Appraisal (DELBI). Results We included 507 CPGs published between 2015 and 2020 in the main analysis. 23/507 (4.5%) of the CPGs achieved the highest DELBI score by including information on funding sources, expenses and the amount of funding provided, as well as a statement on the independence of the guideline authors from the funding institution(s). CPGs with more rigorous methodological requirements (systematic review of the literature and/or structured consensus-building) received higher DELBI scores. Conclusion German CPGs do not communicate their funding transparently. Transparency of CPG funding could be achieved by making it mandatory to publish information for all guidelines. For that purpose, a standardised form and guidance should be developed. (shrink)