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Objective: Temporal lobe injury (TLI) was a debilitating complication after radiotherapy in nasopharyngeal carcinoma (NPC) patients, especially for those who suffered relapses and received re-irradiations.Methods:We explored clinical characteristics and prognostic factors of TLI for locally recurrent NPC patients after re-irradiation by intensity modulated radiotherapy (IMRT).454 temporal lobes (TLs) of 227 locally recurrent NPC patients were reviewed.Clinical characteristics of TLI were analyzed.The equivalent dose in 2Gy per fraction (EQD2) of TLs was recalculated for the two radiation courses to facilitate the comparability of individual data.Results:The median follow-up time was 31 months (range, 3-127 months).31.3% (71/227) patients developed TLI after re-irradiation by IMRT.The median latency of TLI was 15 months (range, 4-100 months).The univariate and multivariate analysis showed that the interval time (IT) between two irradiations and the summation of maximum doses of the two radiation courses (EQD2-Σmax) were independent factors for TLI.The 5-year incidence of TLI for IT≤26m or >26m was 35.9 vs.53.7% (p=0.024).The median maximum doses delivered to the injured TLs were significantly higher than uninjured TLs after two courses of radiotherapy (135.3 vs.129.8Gy, p<0.001).The incidence of TLI with EQD2-Σmax<125Gy is<5%, and that with EQD2-Σmax<145Gy is <50%.Treatment mode limiting EQD2-∑max< 125Gy with a more than 2-year interval was relatively safe.