Background 17 alpha-Hydroxylase deficiency, a rare form of congenital adrenal hyperplasia, presents diagnostic and treatment challenges because of the limited number of cases reported.Case summary This report discusses the case of a 17-year-old Chinese girl who suffered from unexplained dizziness, headaches, and high blood pressure. She had amenorrhoea during puberty and had been diagnosed with ovarian delay. Initially, she was diagnosed with hypertension and received three antihypertensive medications. However, her blood pressure remained poorly controlled. Gene sequencing revealed 17 alpha-hydroxylase deficiency caused by compound heterozygous mutations in CYP17A1. One of the mutation sites, potentially novel, has not been reported previously. Subsequently, dexamethasone therapy was initiated, her blood pressure was controlled, and the symptoms disappeared. During the 1-year follow-up, her blood pressure remained normal, and the symptoms did not recur.Discussion 17 alpha-Hydroxylase deficiency is a rare cause of secondary hypertension. Despite the low prevalence, it should not be overlooked in younger patients.