Etiology of premature ovarian failure (POF) is unclear in most patients. Since some cases are related to X-chromosome abnormalities, cytogenetical studies were conducted in patients with POF. Lymphocyte cultures from eleven patients were compared to cultures from age-matched controls. All individuals presented normal karyotypes. Frequencies of aneuploid and structural chromosome aberrations did not differ between the groups. The X chromosome was more frequently involved in aneuploidy and in premature centromere division in both groups.