 This paper proposes a new method called voxel-based marked neighborhood searching, VMNS, to detect and measure street trees from 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 pole-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 authored by Hongxing Liu, Giant Pain Wu, Yan Huang, and others.