A 2-month-old breast-fed baby is described, who, admitted for a prolongation of the QT interval on ECG, was found to be severely hypokalemic, alkalotic and hypertensive (blood pressure 200/100 mm Hg). Marked generalized hypotonia was present, and length was less than 3% for age. The results of endocrinological evaluation showed profound suppression of the pituitary-adrenal function and of the renin-aldosterone mechanism. CT scan, cavography and pyelography were normal. A pharmacological cause for the symptoms was sought and found: the mother had been using for the care of bruised nipples a cream containing 1% 9-alpha-fluoroprednisolone-21-acetate. Blood pressure remained elevated for 6 months, but became normal after one year, and growth has resumed normally. The possible differential diagnoses are considered, and the risks presented by topical steroids are emphasized.