Congenital lipoid adrenal hyperplasia (lipoid CAH) is the most severe form of CAH, eventually destroying all adrenal and gonadal steroidogenesis. Lipoid CAH is caused by mutations in the steroidogenic acute regulatory protein (StAR), which facilitates the entry of cholesterol into mitochondria to initiate steroidogenesis. Patients with lipoid CAH typically present with a salt-losing crisis in the first 2 months of life, although presentation as late as 10 months with partial retention of StAR activity has been reported. We describe eight patients from six Saudi Arabian families who were first diagnosed at 1-14 months of age (median, 4-7 months; mean, 7 months). Five patients were 46,XY, and three were 46,XX. At presentation, all had hyponatremia, hyperkalemia, elevated ACTH, and low cortisol. Pregnenolone, progesterone, 17-hydroxypregnenolone, 17-hydroxyprogesterone, testosterone, androstenedione, and dehydroepiandrosterone sulfate were all low in those patients in whom it was measured. DNA sequencing showed that one patient was homozygous for the StAR mutation M144R, and the other seven, from five apparently unrelated families, were homozygous for the StAR mutation R182H. Each mutation was recreated in a human StAR cDNA expression vector and found to be wholly inactive in a standard assay of COS-1 cells cotransfected with the cholesterol side-chain cleavage enzyme system. Thus, the loss of all assayable activity in vitro correlated poorly with the later onset of clinical symptoms in these patients. Lipoid CAH may present much later in life than previously thought.