We assessed the value of perinatal autopsy following mid-trimester termination of pregnancy due to major fetal trisomies. Singleton fetuses (n=305) that underwent prenatal sonography and karyotyping during the second trimester of pregnancy and that had trisomy 21, trisomy 18, or trisomy 13 constituted the study population. The findings of second trimester sonography and fetal autopsy were compared. Altogether, 611 separate major structural malformations were diagnosed during autopsy. Full agreement was achieved between sonography and autopsy in 35.8% of the malformations. The additional findings at autopsy (64.2%) involved mainly two organ systems: face, including ears and eyes, and extremities, including hands and feet. Some ultrasound findings were not confirmed at autopsy (n=49). Concordance rates between sonography and autopsy findings regarding soft markers were considerably high in cases of increased nuchal fold thickness and short femur/humerus. On the other hand, fetal autopsy was of limited value as far as hyperechoic bowel and echogenic intracardiac foci are concerned. Pathologic examination provides additional information regarding many fetuses with aneuploidy, and may indicate possible directions of sonographic screening for major chromosome aberrations. However, prenatal sonography and perinatal autopsy should be considered as complementary ways of increasing our knowledge about the possible features of fetal aneuploidies.