This is a case report of 46,XY female phenotype (46,XY karyotype, no pubic hair, blind vagina and absence of uterus)in an 18-year-old patient. To confirm whether a Y chromosome has a structural abnormality, fluorescent in situ hybridization (FISH) with the chromosome X/Y cocktail probe was simultaneously performed, and the six loci [PABY, RPS4Y(sy16, sy17), ZFY, DYS14] on the short arm, one locus (DYZ3) on the centromere and one locus (DYZ1) on the long arm were amplified by polymerase chain reaction (PCR). The probes used FISH hybridized to centromere of the X chromosome and heterochromatin region (Yq12) of the Y chromosome, and all PCR related Y chromosome showed positive band like normal male. From the results obtained, it seemed that the Y chromosome from the 46,XY female was structurely normal. Especially, the SRY gene has been equated with the mammalian testis-determining factor, and absence or point mutation in the SRY gene causes XY female. To detect the point mutations of SRY sequences, single-strand conformation polymorphism (SSCP) assay was used. Our results confirm that this patient has no mutation in the SRY gene on the Y chromosome.