Purpose: To evaluate the cytogenetic results of cord blood samples and apply fluorescence in situ hybridization (FISH) as an additional technique to "46,XX cytogenetically diagnosed cases" in order to confirm the karyotypes or to verify the occurrence of a Y chromosome component. Methods: 111 cord blood specimens were cultured for prenatal karyotyping. Of the 66 "46,XXkartoyped" materials, 20 of them were painted with X (DXZ1) and Y (DYZ3) chromosome ?-satellite probes by FISH. Results: Of the 111 cases, 106(95.5%) were karyotypically normal, and 5 (4.5%) were abnormal (two regular and one mosaic trisomy 21, one X mosaicism and one pericentric inversion of chromosome 9). In one of the 20 "46,XX" karyotyped cord blood specimens, 104 of 500 cells (20.8%) revealed one X signal and one Y signal. Conclusion: The evaluation of abnormal and 46, XY karyotypes in cord blood samples gave accurate results but "46,XX" karyotypes must be confirmed with an additional technique like FISH for an accurate cytogenetic evaluation of specimens.