ObjectivesTo establish the implications of frailty as a predictor of outcome in patients with head and neck cancer requiring flap repair.DesignRetrospective cohort.Data sourceWe captured data from patients above 60 years old undergoing head and neck tumour resection and free flap reconstruction surgery between June 2019 and June 2020 at the Department of Oral and Maxillofacial Surgery, Sun Yat-sen Memorial Hospital, Sun Yat-sen University. The data contain all treatment information.Outcome variablesSurgery repeated in 30 days, postoperative complications, hospital length of stay, postoperative main biochemical standards.Exposure variablesAge, sex, smoking history, alcoholism history, American Society of Anesthesiologists score, National Nosocomial Infection Surveillance score and Clinical T staging were exposure variables. The frailty index is the main variable.ResultA total of 254 patients were included in this study. Among them, 124 patients were classified as frail, while 130 patients were classified as non-frail. We found that frail patients stayed in the hospital longer than non-frail patients after surgery (p=0.018). According to the data of 26 frail patients who directly entered the intensive care unit (ICU), we found that these patients had a lower leucocyte count (p=0.005).ConclusionsFrailty is a useful predictor of outcomes in patients undergoing head and neck cancer surgery with flap reconstruction. Frailty can be a clinical tool used to identify high-risk patients and guide perioperative care to optimise patient outcomes. Frail patients have better outcomes if they directly enter the ICU.