This paper proposes a method for extracting teniae coli from abdominal CT volumes. In CT colonography, two types of CT volumes are taken in prone- and supine-positions. These images are used for preventing misdiagnosis caused by fluid stool. However, since the shape of the colon easily changes, it is difficult to find correspondences between such two volumes. Radiologists need to carefully read both prone- and supine-position volumes. This imposes heavy loads on radiologists who need to CT volumes for CT colonography. Development of a method for registering prone- and supine-position volumes to assist diagnostic process is strongly expected to be developed for reduction of radiologists' load. This paper shows a fully automated method to extract teniae coli regions, which are one of promising land marks of the colon, from CT volumes. Teniae coli region information would be useful for registering CT volumes taken in prone- and supine-positions. Since teniae coli are observed as sequences of ridge-breaks traversing haustral folds, they can be extracted by analyzing positions of the haustral folds. First, we extract haustral folds regions based on curvatures on the colonic wall. Three-lines passing through gravity centers of haustral folds are computed. Teniae coli regions are extracted as lines running between these three lines. We applied the proposed method to eight cases of colonic CT volumes. The experimental results showed that the proposed method was able to extract teniae coli satisfactorily for cases where haustral folds were extracted correctly.