In the work of Peng et al. (Appl Math Comput 218(21):10406–10412, 2012), a new measure was proposed for fault diagnosis of systems: namely g-good-neighbor conditional diagnosability, which requires that any fault-free vertex has at least g fault-free neighbors in the system. In this paper, we establish the g-good-neighbor conditional diagnosability of locally twisted cubes under the PMC model and the MM^∗ model.