Cushing's disease (CD) presents a marked female preponderance, but whether this skewed gender distribution has any relevance to the presentation and outcome of CD is not known. The aim of the present study was the comparison of clinical features, biochemical indices of hypercortisolism, and surgical outcome among male and female patients with CD. The study population comprised 280 patients with CD (233 females, 47 males) collected by the Italian multicentre study. Epidemiological data, frequency of clinical signs and symptoms, urinary free cortisol (UFC), plasma ACTH and cortisol levels, responses to dynamic testing, and surgical outcome were compared in female and male patients. Male patients with CD presented at a younger age, compared with females (30.5 +/- 1.93 vs. 37.1 +/- 0.86 yr, P < 0.01), with higher UFC and ACTH levels (434.1 +/- 51.96 vs. 342.1 +/- 21.01% upper limit of the normal range for UFC, P < 0.05; 163.9 +/- 22.92 vs. 117.7 +/- 9.59% upper limit of the normal range for ACTH, P < 0.05). No difference in ACTH and cortisol responses to CRH, gradient at inferior petrosal sinus sampling, and cortisol inhibition after low-dose dexamethasone was recorded between sexes. In contrast, the sensitivity of the high-dose dexamethasone test was significantly lower in male than in female patients. Of particular interest, symptoms indicative of hypercatabolic state were more frequent in male patients; indeed, males presented a higher prevalence of osteoporosis, muscle wasting, striae, and nephrolitiasis. Conversely, no symptom was more frequent in female patients with CD. Patients with myopathy, hypokalemia, and purple striae presented significantly higher UFC levels, compared with patients without these symptoms. Lastly, in male patients, pituitary imaging was more frequently negative and immediate and late surgical outcome less favorable. In conclusion, CD appeared at a younger age and with a more severe clinical presentation in males, compared with females, together with more pronounced elevation of cortisol and ACTH levels. Furthermore, high-dose dexamethasone suppression test and pituitary imaging were less reliable in detecting the adenoma in male patients, further burdening the differential diagnosis with ectopic ACTH secretion. Lastly, the postsurgical course of the disease carried a worse prognosis in males. Altogether, these findings depict a different pattern for CD in males and females.