A de novo structural abnormality of one X chromosome was prenatally detected in a female fetus. This chromosomal abnormality has been analyzed by conventional cytogenetic methods, fluorescence in situ hybridization, and laser scanning image cytometry. The association of these techniques has demonstrated that this anomaly corresponds to a (X;X) translocation. Analysis of hybridization signals by laser scanning image cytometry allowed to localize that the breakpoints were at the X-centromeric region and Xp11.3, respectively. These results show the usefulness of image analysis and fluorescence in situ hybridization for a rapid characterization of de novo structural chromosome anomalies in prenatal diagnosis.