The authors describe a case of Parinaud's syndrome in a 14-year-old boy with delayed puberty. The neurological examination and the neuroradiological work-up excluded the presence of cerebral pathological processes except for a pituitary microadenoma. As the sole presence of the microadenoma cannot justify gonadotropin deficiency, the authors in this case favor a form of isolated gonadotropin deficiency, and they suggest that the elevation paralysis can be put in the range of median line defects, such as labiopalatoschisis and hypoplasia of the olfactory bulbs, frequently associated with isolated hypogonadotropic hypogonadism.