Cushing's syndrome is considered a rare disease and its diagnosis can be challenging. Establishment of evidence-based recommendations is difficult. In 2008, several national and international consensus recommendations for the diagnosis or management of Cushing's syndrome were reported. The Endocrine Society, with the participation of the European Society of Endocrinology, has developed a task force to update recommendations for the diagnosis of Cushing's syndrome. The main aspects of these recommendations are presented in this article and discussed in the context of current research efforts in Europe focusing on the improvement of diagnosis and management of rare diseases including adrenal disorders such as Cushing's syndrome.