we propose an algorithm for the semiautomatic segmentation of medical image series based on the combination of the live wire algorithm and the active contour model.We modify the traditional live wire algorithm by combining it with the region growing method and obtain accurate segmentation of one or more slices in a medical slice series by the live wire algorithm.Then the computer will segment the nearby slice using the active contour model.We introduced a gray-scale model to the boundary points of the active contour model to record the local region characters of the desired object in the segmented slice and replace the external energy of the traditional active contour model with the energy decided by the gray-scale model.A simple method based on the idea of the live wire algorithm is introduced for the reparation of the automatic segmentation result to guarantee the reliability of the result.Experiment shows that our algorithm can obtain the boundary of the desired object from a series of medical images quickly and reliably with only little user intervention.