This study aimed to evaluate magnetic resonance (MR) imaging appearances of 11 gastrointestinal stromal tumors in the abdomen and pelvis and compared them with some histological findings. Gastrointestinal stromal tumor showed nonhomogeneous signal intensity and included hemorrhage in large tumors. Gastrointestinal stromal tumors showed a wide variety of enhancement, and contrast enhancement of the tumor was consistent with mitosis index as well as the largest diameter of the tumor. Contrast-enhanced MR imaging may be useful in the assessment of tumor activity.