Objective To evaluate the outcome of preoperative therapy with ketoconazole (KTZ) and/or metyrapone (MTP) in previously untreated patients with Cushing's syndrome (CS). Design and patients Sixty-two patients with CS (85% ACTH dependent), treated with steroidogenesis inhibitors prior to surgery between 1983 and 2010, were retrospectively studied. T0 and t1 defined baseline and end of preoperative medical treatment. Results Outcomes were based upon clinical and biochemical (normal UFC) control of hypercortisolism at t1: group CO (controlled) included 20 patients (32%) with eucortisolism and significant clinical improvement; group NC (not controlled) 30 (48%) with persistent hypercortisolism and no control of symptoms; and group PC (partially controlled) 12 patients (19%) who despite eucortisolism had no real clinical improvement. Median duration of treatment was 4 months (range: 1-30·7), and median cumulative dose of KTZ and MTP was 57 g (range: 3·6-240) and 120 g (range: 7·5-1215). CO patients were treated more with KTZ alone than the other groups (P < 0·05). MTP alone was administered more in PC than in CO patients (P < 0·01). No clinical differences were observed between groups at baseline. Systolic blood pressure at t1 was higher in PC than in NC patients (P < 0·05). Hypertension persisted more in PC patients than in the other groups (P < 0·05) after a median postsurgery follow-up of 108 months (range: 4-276). Conclusions Preoperative administration of KTZ, MTP or both normalized UFC in 52% of patients with CS, but concomitant clinical improvement did not always follow. Larger, multicentre studies are needed to individualize preoperative medical treatment and improve outcome in patients with CS. © 2012 Blackwell Publishing Ltd.