Purpose : To demonstate and evaluate the value of MRI findings of the TSH(Thyroid-Stimulating Hormone, TSH,Throtropin)-secreting pituitary adenoma. Materials and Methods : The authors reviewed retrospectively the MRimages of 4 patients with TSH-secreting pituiatary adenoma. Evaluation of the anatomical location, signalcharacteristics, enhancement patterns, size, shape and circunferential changes were made. Results : Nocharacteristic common MR findings in size, shape, signal intensity, and circumferential changes of TSH-secretingpituiatary adenoma waere observed among 4 cases (size; 5X7mm to 10X11mm, shape;ovoid to round, signalintensity;high in 1 case on T1 and T2W1, isosignal intensity in the other 3 cases, circumferential change;stalkdeviation in 1 case, no stalk deviation in cases). But, the tumors were centrally located at the anteriorpituitary gland and showed relatively homogeneous signal intensity on MR images of all 4 patients. Conclusion : Weconclude that centrally-located mass at the anterior pituitary gland with homogeneous signal intensity on MR imagemay be suggestive of the TSH-secreting pituitary adenoma, although the MR findings are not specific for thedisease.