Magnetic resonance (MR) imaging was performed in fifty normal pituitary glands, ten pituitary microadenomas, and twelve adenomas with extrasellar extension using a 0.15 Tesla resistive magnet. The average height of normal glands was 5.6 +/- 1.2 mm, whereas that of microadenomas was 6.8 +/- 1.0 mm. The superior surface and internal texture of these conditions were well delineated. Adenomas that showed extrasellar extension together with surrounding structures were well demonstrated on sagittal and coronal scans. It can be expected that with further technical developments MR imaging will play an important role in the clinical management of pituitary adenomas.