Magnetic resonance images of the pituitary-hypothalamic area in patients with GH secretory disorders, divided into two groups (hypersecretory and hyposecretory), were studied. In the first group there were 42 patients with pituitary adenoma; size, signal characteristics, direction of growth, and type of enhancement were analyzed and compared with similar studies in 40 age and sex matched control patients with non-GH secreting pituitary adenomas. No significant differences were found except for a higher frequency of chiasm involvement and a more pronounced contrast enhancement in the control group. The hyposecretory group was composed of 101 patients with congenital idiopathic growth hormone deficiency (CIGHD). MR revealed morphological abnormalities consisting of hypoplastic anterior pituitary and ectopic posterior pituitary (PPE) in 59 patients, without evidence of a complete pituitary stalk; in 42 patients the posterior pituitary was in normal position and the pituitary stalk visible. The group with PPE showed a greater frequency of multiple pituitary hormone deficiency (51% vs 12%), breech delivery (30% vs 7%) and associated congenital brain anomalies (12% vs 7%). These data suggest that CIGHD could be the result of a congenital midline brain anomaly in a significant proportion of patients.