Purpose Residual margin dysplasia is a cause of disease failure in SCCHN. The LIHNCS trial is a multicenter RCT assessing the effectiveness of Lugol’s iodine vital staining to reduce margin dyplasia at resection of Oral and Oropharyngeal squamous cell carcinoma (SCC). We report interim data on recruitment centres and numbers, patient acceptability, patient demographics and risk factors to date in the study. Materials and methods Patients are randomized to either gold standard SCC resection with 1 cm clinical margin or to resection using Lugol’s iodine solution. Lugol’s solution demonstrates absence of glycogen in non-orthokeratinised squamous epithelia and this correlates with presence of dysplastic change. Reporting pathologists are blinded to study arm of patients recruited. Pathology outcomes are re-reported centrally. The study is powered to recruit 300 patients. Results At time of writing 177 patients have been recruited in 14 centres. 12 other centres are in set up. Patient acceptability remains high at 90.7%. There have been isolated cases of patients refusing to participate and insisting on use of Lugol’s iodine for their treatment. There have been six deaths and 13 serious adverse events. None of these SAEs are believed to be related to the trial intervention. T1 and T2 cancers make up 75.8% of cases recruited. Regarding N stage; 79% are N0, 11.5% N1 and 9.6% N2. Interestingly, 26.1% of patients in the trial have never smoked tobacco. 36.6% are exsmokers and 37.3% current smokers. Surgeon compliance is high; Lugol’s arm 97%, control arm 98.6%. Conclusion This multicentre RCT studying patients undergoing major surgery for SCC of the oral cavity and oropharynx is proceeding well for recruitment and return of trial CRF data. Patients recruited show an interesting pattern of risk factor behavior. A higher than anticipated proportion have never smoked tobacco.