The constitutional translocation between chromosomes 11 and 22, t(11;22)(q23;q11), is the most frequent chromosomal rearrangement in humans. The risk of having an imbalanced child is greatly increased for the women carrier as compared to men carrier. We found 3 cases with familial translocation t(11q;22q). In these families fetal chromosomal rearrangements were detected by amniocenteses which were ordered because of the advanced maternal age, the abuse of drugs or previous fetal loss. We perform chromosome analysis of parents to identify the origin of fetus` karyotype retrospectively using G-banding. Two fetuses were balanced translocation with 46, XX and XY, t(11;22)(q23;q11)pat. Their fathers were detected later to be a balanced translocation carrier. The remaining fetus was examined as an unbalanced karyotype, 47, XX, +der(22). The derivate chromosome 22 has inherited from mother with balanced translocation 46, XX, t(11;22)(q23;q11).