A 56-year-old woman presented with fatigue and headache after receiving four doses of ipilimumab, a monoclonal antibody against cytotoxic T-lymphocyte antigen 4, for the treatment of metastatic melanoma. Low morning serum concentrations of corticotropin (< 1· 1 pmol/L [reference range 2· 2–13· 2 pmol/L]) and cortisol (41· 4 nmol/L [reference range 165· 5–662· 2 nmol/L]), combined with pituitary enlargement, were consistent with hypophysitis-related secondary adrenal insufficiency. Treatment with a replacement dose of hydrocortisone was initiated. Before ipilimumab treatment, her adrenal glands (circled) were normal in size (figure A). A subsequent surveillance CT scan of the abdomen showed bilateral enlargement of adrenal glands (figure B). Her serum cortisol and aldosterone concentrations did not respond to cosyntropin stimulation, which indicated primary adrenal insufficiency. 6 weeks later, her adrenal glands normalised in size (figure C). The dynamic size change of the adrenal glands suggests ipilimumab-related autoimmune adrenalitis. Although secondary adrenal insufficiency is a fairly common endocrinopathy related to ipilimumab treatment, the identification of primary adrenal insufficiency that could coexist with secondary adrenal insufficiency is important.