Objective : To explore the incidence of fragile X premutation in patients with idiopathic premature ovarian failure, particularly in the Korean population. Design : A prospective study. Materials and Methods : Eighty-three women affected by idiopathic premature ovarian failure were recruited for this study. Patient with known causes of premature ovarian failure were excluded : cytogenetic abnormalities, prior chemotherapy, prior bilateral oophorectomy. DNA was extracted from peripheral blood. Fragile X (FRAXA) premutation was evaluated by PCR amplification of and Southern blot analysis for FMR1 gene. Results : The FRAXA premutation was detected in three (3.6%) out of 83 patients with idiopathic premature ovarian failure. Conclusion : This result suggests that fragile X premutation screening is indicated in patients with idiopathic premature ovarian failure, particularly in the Korean population.