25% of Cushings syndrome cases are caused by cortisol producing tumours of the adrenal glands. Adrenalectomy is standard treatment followed by glucocorticoid replacement therapy until the hypothalamic-pituitary-adrenal axis recovers. We present a challenging case of adrenal insufficiency after unilateral adrenalectomy for Cushings syndrome. A 38 year-old woman was referred with hyperlipidaemia and uncontrolled hypertension diagnosed 4 years previously. Examination revealed Cushingoid features and a review of previous tests performed abroad revealed likely Cushings. Overnight dexamethasone suppression testing showed a cortisol of 429 nmol/l and an undetectable baseline ACTH. CT imaging confirmed a 3 cm left adrenal mass. A laparoscopic left adrenalectomy was performed. Post-operatively 10 mg thrice daily of hydrocortisone was commenced with a view to wean. On attempts to taper the dose the patient developed severe proximal myalgia, which persisted for 10 months post-operatively. A rheumatological screen was negative. A hydrocortisone day curve showed cortisols of <20 nmol/l (0 min), 319 nmol/l (120 min), 263 nmol/l (240 min) and 299 nmol/l (360 min). She also developed severe anxiety, despite resolution of her hypercortisolaemia. She required referral to psychological services. 12 months post-adrenalectomy her symptoms improved so the hydrocortisone was reduced to 10/5/5 mg. Short synacthen testing confirmed no HPA axis recovery and after 22 months she remains on hydrocortisone replacement. Cortisol producing tumours are known to suppress the HPA axis, forming the basis of steroid replacement postoperatively. Replacement can be highly variable, but a review published by Di Dalmazi et al. indicated that the average time to recovery of adrenal function post unilateral adrenalectomy for these tumours was 11 months. Our patient had overt Cushings for over 4 years prior to surgery which may explain the failure to recover her axis and her clinical symptoms on attempts to reduce her steroids. Additionally, some studies have reported an exacerbation of psychiatric symptoms with cortisol decrease.