Transsphenoidal surgery (TSS) is the treatment of choice in Cushing's disease. However, recurrence rates are substantial and currently there are no robust predictors of late prognosis. As accumulating evidence challenge the accuracy of the traditionally used early postoperative cortisol values, alternative tests are required. The study of Cambos et al., published in a recent issue of the European Journal of Endocrinology, adds to the existing data that support a role of the desmopressin test as an early and reliable predictive marker in successfully TSS-treated patients. However, despite these promising data, the use of this test is hampered by the fact that it can be applied only in patients with a documented preoperative positive test. Moreover, the lack of robust criteria to define positive postoperative responses represents another major limitation.