Our aim was to investigate the contribution of certain antenatally detectable markers leading to the diagnosis of trisomic fetuses we observed over a period of 6 years. In our study, we specifically analyzed the role played by advanced maternal age and sonographically discovered abnormalities in the detection of autosomal trisomies. All together, 27 fetuses had this disorder, representing 28.7%(27 of 94) of all cytogenetic aberrations detected at our center over the same period. Down syndrome (12 cases) and Edward syndrome (11 cases) were the most common trisomies, while 4 cases of Patau syndrome were also diagnosed. The most commont indication leading to diagnosis was abnormal ultrasound finding (48.2%), followed by advanced maternal age (44.4%). However, 63% of the trisomic fetuses belonged to mothers aged 35 years and above. Down syndrome fetuses (41.7%) had prenatally detected sonographic anomalies, 63.6% for Edward syndrome, and all fetuses with Patau syndrome (4 of 4) showed abnormal sonographic signs. Trisomy 21 presented with the following features: hydramnios, complex malformations, pyelectasis, and duodenal atresia. Trisomy 18 fetuses showed hydramnios, intrauterine growth retardation, microcephaly, spina bifida, and nonimmune hydrops fetalis. Signs observed in fetuses with trisomy 13 were: hydrocephalus, intrauterine growth retardation, oligoanhydramnios, complex malformations, severe fetal bradycardia and hydronephrosis.