For patients treated with lung stereotactic body radiation therapy (SBRT) using dynamic conformal arcs, the influence of inhomogeneity correction (IC) on normal tissue and tumor dosimetry was studied. For the same numbers of monitor units, the planning target volume equivalent uniform doses calculated without path-length IC were lower than those calculated with IC (mean difference 18%, range 1-34%; p < 0.0001). Normal lung dose differences were of the same magnitude in opposite direction. In reports of SBRT, it will be helpful to maintain clear communication about the type of IC used to avoid future uncertainties about true normal tissue tolerance and tumor dose-response relationships.