 This paper proposes a new method called voxel-based marked neighborhood searching, the MNS, to detect and measure street trees for mobile laser scanning, MLS, data. The method consists of six steps, voxelization, calculation of values of voxels, searching and marking neighborhoods, extraction of potential trees, derivation of morphological parameters, and elimination of pull-like objects other than trees. The method was tested on two case studies and showed high accuracy and completeness. The derived morphological parameters, such as tree height, crown diameter, dbh, and cbh, were found to be in good agreement with field measurements. This article was offered by Hongxing Liu, Jianpeng Wu, Yan Huang, and others.