Results after radiotherapy, alone or combined with surgery, applied prior to 1982 in 1700 patients with localized ENT tumors showed 669 (39%) of T and/or N failures and isolated second ENT localizations. Therapeutic recovery operation was performed in 263 of these 669 cases (39%). For the 324 cases of isolated T failures, 31% had recovery treatment, with a level varying between 15% for base of tongue and 55% for laryngeal tumors. Frequency of treatments varied with initial TNM (18% for T3-T4 and 47% for T1-T2) and initial treatment (26% after combined radiotherapy-surgery and 32% after radiotherapy alone). Surgery had been the main treatment (74%) followed by curietherapy (19%). Overall control rate was 55.5%. The 3 year survival rate for all isolated T failures treated was 31%, with survival medians of between 8 and 44 months as a function of initial localization. For the 156 cases of isolated N failures, 62% had recovery treatment, results varying according to whether it was a case of immediate N failure or a lymph node recurrence. The local control rate was 62.5% globally, the 3 year survival for isolated N failures treated 17.5%. For the 115 T + N failures, recovery treatment was attempted in only 9 cases (7%) but all patients died within 2 years of evolution of the local and regional disease. For the 74 second ENT localizations, 80% had recovery treatment with a global local control of 73% and a 3 years survival of 35%. Recovery treatment for therapeutic ends is therefore a frequently practised procedure (39% of cases).(ABSTRACT TRUNCATED AT 250 WORDS)