The authors describe the case of an adrenal-deficient woman who required high doses of mineralocorticoid replacement in sequential pregnancies. A 22-year-old woman with surgical removal of her adrenals in childhood, on stable mineralocorticoid and glucocorticoid replacement, increased her need for mineralocorticoid during pregnancy. Her requirements increased from 0.3 mg of Fludrocortisone daily to 1.2 mg and 1.4 mg daily in sequential pregnancies based on serum renin activity levels and presence or absence of postural hypotension. To our knowledge, this is the first published case report of the need for high dose mineralocorticoid replacement in a pregnant patient with primary adrenal insufficiency.