Hypothalamic-pituitary (HP) sarcoidosis has 2 main endocrine manifestations: diabetes insipidus and hyperprolactinemia. We conducted the current study to investigate pituitary dysfunction and perform imaging of the HP area in patients both immediately following diagnosis and after treatment. The study included 6 men and 3 women, with a mean age of 30 years at the onset of sarcoidosis. All patients had both hormonal and magnetic resonance imaging (MRI) HP disorders. All patients had anterior pituitary dysfunction, 7 of them with associated diabetes insipidus. Nine patients had gonadotropin deficiency and 3 had hyperprolactinemia. MRI revealed infundibulum involvement in 5 patients, pituitary stalk thickness abnormality in 5, and involvement of the pituitary gland in 2, associated with other parenchymal brain or spinal cord lesions in 6 patients. All patients had multiple localizations of sarcoidosis, and 5 had histologically confirmed sinonasal localizations. Mean follow-up of the HP disorder was 7.5 years. All patients received prednisone. There was no correlation between the number of hormonal dysfunctions and the area of the HP axis involved as assessed by MRI. Although corticoid treatment was associated with a reduction of radiologic lesions, only 2 patients had partial recovery of hormonal deficiency. In conclusion, hormonal deficiencies associated with HP sarcoidosis frequently include hypogonadism (all patients) and to a lesser degree diabetes insipidus (7 of 9 patients). MRI abnormalities improved or disappeared in 7 cases under corticosteroid treatment, but most endocrine defects were irreversible despite regression of the granulomatous process. Most cases presented with multivisceral localizations and an abnormally high proportion of sinonasal localizations.