Objective To study the efficacy of late course accelerated fractionation(LCAF) radio- therapy in the treatment of nasopharyngeal carcinoma(NPC).The end-po s were local control,radiation-in- duced complications,factors influencing survival.Methods From December 1995 to April 1998,178 NPC patients were admitted for radiation treatment.The radiation beam used was ~(60)Co?or 6 MV X-ray.For the first two-thirds of the treatment,two daily fractions of 1.2 Gy were given to the primary lesion ,with an interval of≥6 hours,5 days per week to a total dose of 48 Gy/40 fractions,over a period of 4 weeks.For the last one third of the treatment,i.e.beginning from the 5th week,an accelerated hyperfractionation schedule was carried out.The dose per fraction was increased to 1.5 Gy,2 fractions per day with an interval of≥6 hours,the total dose for this part of the protocol was 30 Gy/20 fractions over 2 weeks.Thus the total dose was 78 Gy in 60 fractions in 6 weeks.Results All patients completed the treatment.Acute mucosi- tis:none in 2 patients,Grade 1 in 43,Grade 2 in 78,Grade 3 in 52,and Grade 4 in 3 patients.Local control rate:the 5-year nasopharyngeal local control rate was 87.7%,and the cervical lymph node local control rate was 85.7%.The 5-year distant metastasis rate was 26.1%,and 5-year survivals was 67.9%. Sixteen patients had radiation-induced cranial nerve palsy.Conclusions With this treatment schedule, patient's tolerance is good,local control and 5 year survivals are better than control groups of conventional fractionation and hyperfractionation radiotherapy.Radiation-related late complication does not increase.Ran- domized clinical trials are being carried out to further confirm the efficacy of LCAF for nasopharyngeal carci- noma.