A patient with neurofibromatosis type 1 was found to have an enhancing mass in the hypothalamus and in the anterior optic pathway. A 3-month MR study showed a reduction in the size and enhancement of the mass. At a 9-month MR follow-up the mass disappeared and ceased to enhance. This report shows the unusual behaviour of a hypothalamic/chiasmatic mass confirming that in such asymptomatic cases the conservative management can be considered the treatment of choice.