Magnetic resonance imaging (MRI) of the sellar and juxta sellar area was performed in 40 children with idiopathic hypopituitarism. MRI was normal in the 17 patients with partial growth hormone (GH) deficiency and in the 5 patients with GH neurosecretory dysfunction. Among the 18 patients with complete GH deficiency, the 10 with pituitary stalk transection presented more often with perinatal abnormalities, had the most severe GH deficiencies and more frequently multiple hormone deficiencies, in particular TSH deficiency. Pituitary gland size studies showed that the small size of the residual glandular tissue was responsible for these particularities. If MRI is of no great interest for functional GH deficiency, in half of the primary complete GH deficiencies, it enables to visualize a pituitary stalk transection with regeneration of neurohypophysis.