Segmentation is a process of partitioning the data in a triangular model to extract the feature regions for use in surface reconstruction. Quadratic surfaces are among the common entities in typical CAD models and should be reconstructed accurately. The purpose of this study is to develop a method for segmenting quadratic features from triangular meshes. The proposed process is primarily composed of two steps. In the first step, a region growing is developed to search for a small area near a seed point to determine the feature type, which can either be a plane, a spherical surface, a cylindrical surface or a conical surface. In the second step, a re-growing procedure is employed to search for the points of the same feature type. Moreover, an automatic algorithm is proposed to extract all planar regions for complex triangular models. The feasibility and limitations of the proposed method are demonstrated by real range data with various quadratic surfaces. (C) 2009 Elsevier Ltd. All rights reserved.