To report two rare cases of gonadotropin-resistant ovary syndrome associated with secondary amenorrhea and normal levels of inhibin B. Case report. Two university teaching hospitals. Two women presenting with secondary amenorrhea and infertility. The control group for the inhibin B levels consisted of 30 cycling women of reproductive age. Medical history, physical examination, laboratory data, histologic findings, and IVF results. Diagnosis and treatment of resistant ovary syndrome. Case 1 was a 25-year-old woman with secondary amenorrhea and primary infertility. She had high serum levels of FSH and LH, low E(2) levels, and normal inhibin B levels (62 pg/mL). Karyotype was 46,XX, and ovarian biopsy showed primordial follicles with oocytes. Administration of GnRH analogue with hMG for 15 days did not affect E(2) levels. She had a successful pregnancy with IVF using donor oocytes. Case 2 was a 24-year-old woman with secondary amenorrhea. She had elevated serum levels of FSH and LH, low E(2) levels, and normal inhibin B levels (57 pg/mL). Karyotype was 46,XX and ovarian biopsy showed primordial follicles. Administration of GnRH analogue with hMG for 12 days did not affect E(2) levels. Both women were given estrogen-progestin replacement therapy. Inhibin B has a diagnostic role in women with gonadotropin-resistant ovary syndrome associated with secondary amenorrhea. A review of the literature confirms the uniqueness of the diagnostic role of inhibin B in these cases.