We investigated the efficacy and safety of afatinib maintenance therapy in patients with head and neck squamous cell carcinoma (HNSCC) with macroscopically complete resection and adjuvant radiochemotherapy (RCT). This French multicentric randomised phase III double-blind placebo-controlled study included adult patients with ECOG-PS≤2, normal haematological, hepatic and renal functions, and non-metastatic, histologically confirmed HNSCC of the oral cavity, oropharynx, larynx or hypopharynx, with macroscopically complete resection and adjuvant RCT (≥2 cycles of cisplatin 100 mg/m2 J1, J22, J43 and 66Gy (2Gy/fraction, 5 fractions/week, conventional or intensity modulated radiotherapy ≥60Gy). Randomised patients were planned to receive either afatinib (afa arm) or placebo (control arm (C)) as maintenance therapy for one year. Primary endpoint was disease free survival (DFS). A 15% improvement in DFS was expected at 2 years with afatinib (from 55 to 70%). Among the 167 patients with resected HNSCC included in 19 cancer centres and hospitals from Dec 2011, 134 patients were randomised to receive one-year maintenance afatinib or placebo (afa:67; C:67). Benefit/risk ratio was below assumptions and independent advisory committee recommended to stop the study in Feb 2017, the sponsor decided premature study discontinuation, with a 2-year follow-up for the last randomised patient. 2y-DFS was 61% (95% CI 0.48–0.72) in the afatinib group and 64% (95% CI 0.51–0.74) in the placebo group (HR 1.12, 95% CI 0.70–1.80). Maintenance therapy with afatinib compared with placebo following post-operative RCT in patients with HNSCC did not significantly improve 2y-DFS and should not be recommended in this setting outside clinical trials. ClinicalTrials.gov identifier NCT01427478. •The study planned one-year afatinib maintenance therapy (N = 67) or placebo (N = 67).•Afatinib after post-operative RCT showed no improved 2y-DFS in patients with HNSCC.•Afatinib should not be recommended in this setting outside clinical trials.