The simple form of congenital virilizing adrenal hyperplasia was seen in three girls, aged 21 months to 42 months. These children appear unique because they exhibited very mild virilization of the external genitalia and did not manifest acceleration of bone maturation. Posterior fusion of the labia majora obscured the vaginal orifice, resulting in the appearance of a urogenital sinus formation ("pseudourogenital" sinus). It was found that, until at least 4 years of age, girls untreated for this disorder are usually normal in height. Unless the clinician is aware that normal stature and bone age, and mildly abnormal genitalia, are compatible with congenital virilizing adrenal hyperplasia, patients with this disorder may not be properly treated.