Congenital adrenal hyperplasia (CAH) is a congenital, genetic disease due to a decrease in adrenal cortisol synthesis that causes an increase in the ACTH secretion of the pituitary gland, which increases the adrenal gland and increases adrenal androgen secretion. CAH is the most common cause of sexual developmental disorders in people with chromosome 46, XX. Subjects: All people diagnosed with CAH at the Vietduc Hospital in the period 2015–2022. Methods: Retrospective clinical descriptive study. Results: 17 people were diagnosed with CAH aged 4 to 26, chromosomes 46, XX, and had symptoms of masculinization ranging from less to more severe, such as clitomegaly, primary amenorrhee, muscle development, uterus and vaginal undevelopment, polycysteovarian, some patients had complete masculinization. Tests have high testosterone and ACTH, normal cortisol, or low cortisol, depending on the time of sampling. Lifelong treatment with hydrocortisone supplements and increased doses during surgery ensure safety for the patient. Conclusion: CAH is the cause of female masculinization, the late treatment of CAH causes amenorrhee and infertility.