Background:To compare the radiation-induced temporal lobe injury (TLI) in patients with nasopharyngeal carcinoma (NPC) treated with intensity-modulated radiotherapy (IMRT) or two-dimensional conventional radiotherapy (2D-CRT).Patients and Methods: 1276 cases of NPC treated with IMRT or 2D-CRT wereretrospectively reviewed.A diagnosis of TLI was made on follow-up magnetic resonance imaging (MRI).Results: The crude incidence of TLI was 7.5% and 10.8% (P =0.048), and the actuarial 5-year incidence was 16% and 34.9% (P<0.001) for the IMRT and 2D-CRT groups, respectively.Multivariate analysis revealed both T stage (P<0.001) and radiation technique (P<0.001) as independent predictors.Patients with T1, T2 and T3 disease had a significantly higher risk when treated with 2D-CRT (P =0.005,0.016, <0.001, respectively).This trend was not evident for T4patients (P =0.680).The 2D-CRT group had a longer latency for the development ofTLI (P<0.001).Those with T4 disease had a shorter median time to TLI (P =0.006, 0.042, <0.001 when compared with T1, T2 and T3, respectively).Conclusions: IMRT is superior to 2DRT for the management of T1-T3 NPC in terms of sparing the temporal lobe.The high incidence of TLI in T4 disease needs to be addressed.