Heart failure (HF) guidelines recommend routine testing for iron deficiency (ID) and, for those with ID, intravenous iron if the left ventricular ejection fraction is <50%. Guideline adherence to these recommendations by cardiologists in China is unknown.An independent academic web-based survey was designed and distributed via social networks to cardiologists across China. Overall, 1342 cardiologists (median age 34 years, IQR 30-39, 51% women) from all provinces of China completed this survey. More than half were unaware of the need to screen for ID in HF and did not do so routinely in their clinical practice. Approximately 80% were not familiar with the diagnostic criteria for ID in HF guidelines, and only 0.8% recognised transferrin saturation <20% as an independent marker of ID. Regarding iron repletion, only 14% preferred intravenous to oral iron for correcting ID compared with 68% favouring oral iron. Three-quarters were unfamiliar with methods for calculating intravenous iron dose. Furthermore, over 80% were unaware that current guidelines only recommend ferric carboxymaltose or ferric derisomaltose for correcting ID. The main barriers to using intravenous iron were lack of knowledge and experience. Despite such poor awareness and practice, most cardiologists were interested in learning more about managing ID in HF.In this nationwide survey of cardiologists in China, we identified large gaps in both knowledge and management of ID. This survey will help guide the development of educational programmes to improve care for patients with HF and ID in China.© Author(s) (or their employer(s)) 2025. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.