ackground: To compare the dosimetric difference between volumetricmodulated arc therapy (VMAT), intensity-modulated radiotherapy (IMRT), and 3D conformal radiotherapy (3D-CRT) using 6MV for locally advanced lung cancer patients. Methods: A total of 30 treatment plans were calculated retrospectively for ten patients with advanced NSCLC using XIO planning system for 3D-CRT and Monaco Software (Version Monaco Medical Systems Inc., Version 5.11.2.) for IMRT and VMAT. For each case, three different delivery plans (3D conformal radiotherapy 6MV, IMRT, and VMAT) were done. We analyzed the heterogeneity index (HI) and conformality index (CI) of the planning target volume (PTV) and organs at risk (OARs) sparing. Results: The coverage of PTV V95 was significantly better in the VMAT plan than the other two plans. The ipsilateral lung mean dose and its subvolumes showed higher doses in the conformal plan than the VMAT and IMRT plans but with no statistically significant difference. The contralateral lung doses were higher in the VMAT plan and no statistically significant difference between the IMRT and conformal radiotherapy plans. Conclusions: For locally advanced lung cancer patients, VMAT resulted in better PTV coverage than IMRT but with no statistically significant difference and both better than conformal radiotherapy with a statistically significant difference. However, the use of VMAT showed improvements in HI of the target and comparable OAR's sparing with a statistically significant but it showed an increase in V5 and V10 to both lungs, and all the contralateral lung parameters (mean dose, V5, V10, V20, and V30).