Studies in 18 Jewish families from Morocco, Tunis, Turkey and Iran revealed 26 patients with congenital adrenal hyperplasia due to 11 beta-hydroxylase deficiency. The clinical expression of androgen excess varied widely in affected females, and range from solely enlarged clitoris in the mildest forms to severely hypertrophied clitoris with penile urethra and fused labial-scrotal folds in the most extreme forms of masculinization. Intermediate degrees of severity were manifested by ambiguous genitalia. There was no correlation between the degree of virilization and the signs of mineralocorticoid excess. Severe volume-induced hypertension leading to vascular accidents and death were also observed in severe as well as in mildly virilized patients, while completely masculinized females were sometime normotensive. Overt hypokalemia was present in 6 patients but was not a constant feature of hypertensives. However, all affected individuals, except for 2 infants, had very low levels of plasma renin activity suggesting that a state of volume expansion was indeed present in the majority of cases, even though changes in blood pressure did not always occur. The clinical expression of this disorder is characterized by a wide range of variability in the signs of both androgen and mineralocorticoid excess, which do not necessarily correlate with the quantity of hormones secreted.