Ectopic pituitary adenomas (EPAs) are rare lesions. The purpose of this study was to describe the CT and MRI features of sphenoid sinus EPAs. Eight patients with histology-proven EPAs in the sphenoid sinus, all of whom underwent CT and MRI, were reviewed retrospectively. The following imaging features were analysed: (i) size, (ii) margin, (iii) CT attenuation characteristics and (iv) MRI signal intensity. In addition, the involvement of adjacent structures and the time-intensity curve (TIC) of dynamic contrast-enhanced (DCE) MRI were analysed. All EPAs had well-defined margins and showed no relationship to the intrasellar pituitary gland. The mean size was 28 mm (range, 20-46 mm). On non-enhanced CT, the lesions appeared isodense to grey matter in 7 (88%) patients and hypodense in 1 (12%) patient. Only two patients underwent post-contrast CT, and they showed moderate enhancement. On T-1 weighted images, EPAs appeared isointense in 6 (75%) patients and hypointense in 2 (25%). On T-2 weighted images, the lesions appeared hyperintense in 2 (25%) patients and isointense in 6 (75%). EPAs showed mild to moderate heterogeneous contrast enhancement and exhibited a cribriform-like appearance. Two patients underwent DCE MRI; the TIC showed a rapidly enhancing and slow washout pattern. The following features were also seen: an empty sella, bone changes and involvement of the cavernous sinus (5 patients; 62.5%). In conclusion, a high index of suspicion for EPA and a familiarity with the imaging findings may help to diagnose this rare entity accurately.