Evaluation of scoliosis is performed traditionally by means of standing posterior-anterior radiographs of the full spine to assess lateral curvature with the Cobb method. In this paper, we present a new automatic algorithm to measure Cobb angle by using nuclear medicine whole body bone scan images. Our algorithm design is based on the fuzzy sets histogram thresholding, anatomical knowledge-based image segmentation method, and morphology technology. It is expected that the results may help physicians to diagnose scoliosis via the scintigraphy images, and thus to reduce radiation done to patients.