Objective: To investigate the chromosome abnormalities in at risk pregnant women using fetal cells obtained from amniotic fluid at second trimester Materials and Methods: A total number of 502 amniotic fluid samples were referred for chromosomal investigation to the Cytogenetics unit of Sarem Women’s hospital for the past two years. Referral reasons included advanced maternal age (38%), abnormal maternal serum screening test (37%), previous abnormal child (10%), recurrent miscarriages (8%), abnormal sonography (2%), one parent with translocation (1.6%), and other reasons (3.4%). Three cultures were set up for each sample using amniomax/Ham's F10 media. The karyotype was carried out using standard GTG banding technique on the prepared chromosme spreads. A minimum of 20 cells were examined. Results: Culturing success rate was 99.6%. Karyotype results are as follows: 47% of samples were male and 53% appeared as female karyotype. 27 out of 502 (5.4%) had abnormal karyotypes including trisomy 21, triploidy, Klinefelter syndrome, balanced and unbalanced autosomal translocations. The balanced rearrangements included 46, XX, t(4:6) (q31.3; q26.1) mat, 46, XY, t(2;11) (q23;p15) mat, 46, XX, t(8;13) (q24.3q14.1)mat, 46, XY, t(1;18) (p31; q21.3), 46, XY, t(4;9) (q25;q22) mat, and 46, XY, inv (7) (p22q11.23). Two of the cases had a bisatellited marker chromosome. The sex chromosome abnormalities were 47, XXY, 47, XXX, and 46, XY [/47, XYY/45, X. The majority of abnormal cases (40%) were due to abnormal maternal serum screening test, followed by advanced maternal age (37%). Conclusion: Our findings emphasis the importance of maternal serum screening for the detection of chromosome abnormalities in the fetus for at risk pregnancies.