Non-iatrogenic Cushing's syndrome is an uncommon endocrine disease with an estimated annual incidence of 0.7-2.4 cases per million.1 If untreated, Cushing's syndrome is associated with appreciable morbidity and premature death.2 3 The presenting clinical features may be non-specific, and the disease often remains undiagnosed for a considerable time. Spontaneous rupture of the Achilles tendon is unusual, but is well described in patients receiving long term steroid treatment.4^–7 The incidence of spontaneous rupture of tendons in non-iatrogenic Cushing's syndrome is unknown. We report two patients with non-iatrogenic Cushing's syndrome who presented with spontaneous rupture of the Achilles tendon, one to an outpatient orthopaedic clinic and the other to an accident and emergency department. The diagnosis of Cushing's syndrome was made one month later in the first …