Objective To investigate efficient diagnosis and treatment of 17α-hydroxylase (17OHD) deficiency by summarizing clinical characteristics of those patients.Methods From January 1983 to January 2010,48 cases with 17OHD in Peking Union Medical College Hospital were studied retrospectively.Results Among 48 patients with 17OHD,karyotype analysis showed,12 cases with 46,XX and 36 cases with 46,XY.The 46,XX karyotype and 46,XY karyotype with complete 17OHD had typical clinical presentation of amenorrhea [ 12/12,100％ ( 36/36 ) ],no typical spontaneous puberty [ 12/12,13.9％ (5/36) ],Hypertension [ 11/12,100％ ( 36/36 ) ],hypokalemia [ K +:( 2.6 ± 0.7 ),( 2.8 ± 0.7 )mmol/L],hypergonadotropin [ follicle-stimulatinghormone ( FSH ):( 51 ± 35 ),( 79 ± 46 ) U/L,luteinizing hormone( LH ):( 27 ± 14 ),(49 ± 37 ) U/L ],impaired production of sex hormones [ testosterone(T):0.003,0.005 nmol/L; estradiol ( E2 ):26.86,10.64 pmol/L ],hyper-progesterone [ (P):( 32 ± 15 ),( 29 ± 23) nmol/L],impaired production of 17α-hydroxyprogesterone ( 17α-OHP ) [ ( 2.5 ± 1.1 ),( 2.4 ±1.7) nmol/L],ACTH hypersecreation (91.8,114.0 pmol/L).ACTH stimulating test did not elevated in 17α-OHP and cortisol.Conclusion When patients with elevated basal serum levels of progesterone higher than that of ovulation period in addition to clinical symptoms,examination about 17OHD should be warranted.