In this study the presence of pituitary-hypothalamic abnormalities was searched by magnetic resonance (MR) imaging in 30 children (18 males and 12 females, aged 7.4 to 23 years) with isolated growth hormone deficiency (IGHD). Small anterior pituitary was demonstrated in 18 patients and ectopic posterior pituitary (EPP) in four of them. Pituitary stalk was found to be thin in two patients with anterior pituitary hypophasia and EPP and was visible only in post-gadolinium images. In one patient, a hypothalamic mass was found and the bright spot of the posterior pituitary was found without diabetes insipidus, possibly due to a variation in the intensity of the bright signal. Eight patients had normal pituitary imaging suggesting functional damage. In all five patients with familial growth hormone deficiency the anterior pituitary was hypoplastic. We conclude that a high percentage of patients with IGHD had anomalies of the hypothalamo-pituitary region, which could be demonstrated by MR imaging. Furthermore, the low frequency of perinatal abnormalities in these patients suggested developmental defect as the cause of the morphostructural abnormalities. The presence of the familial cases with the same defect pointed to the genetic origin in some instances.