Diabetes insipidus (DI) is thought to be a relatively common complication after craniotomy procedures. To identify subsets of patients at risk for this problem, the postoperative courses of 135 consecutive patients undergoing craniotomy were scrutinized retrospectively. All patients received similar anesthetic management and all were hospitalized in the ICU postoperatively. DI developed in 9 (5 transient, 4 permanent) of 135 patients (6.7%). All 9 patients developing DI had undergone craniotomy for treatment of a pituitary disorder. It is concluded that postcraniotomy DI is a problem almost exclusively observed in patients with pituitary/hypothalamic disease and that DI rarely occurs in patients with other types of intracranial pathology.