Background: Holoprosencephaly (HPE) is a complex brain malformation characterized by impaired midline cleavage of the embryonic forebrain. Syntelencephaly (SE) is an uncommon and distinct subset of holoprosencephaly. In cases with syntelencephaly, hemispheric fusion does not occur at rostral forebrain but rather across posterior frontal region. Here we report ultrasound and magnetic resonance findings of a fetal case with syntelencephaly, which is an extremely rare prenatal diagnosis, and its correlation with fetal autopsy. Case Presentation: A 20-year-old woman gravida 2, para 1 at 26 th week of gestation was referred to our perinatology unit for second opinion ultrasound (US). The couple was third degree consanguine and their first child suffered from hearing loss with no detectable etiology. On axial and sagittal planes of grayscale US, bilateral ventriculomegaly, absence of cavum septum pellucidum and interventricular septum with the presence of interhemispheric fissure and suspected agenesis of corpus callosum were detected. Additionally, coronal examination revealed suspected cerebral hemispheric fusion and absence of interhemispheric fissure near the fetal vertex. Fetal cranial magnetic resonance imaging (MRI) revealed dilatation at all anatomic regions of lateral ventricles and no interventricular septum. Interhemispheric fissure was present at anterior frontal and occipital regions. However, the middle part of the interhemispheric fissure was absent and the fusion of both hemispheres was evident between posterior frontal and parietal regions. Additionally, the midbody of corpus callosum was absent. These findings were considered as the characteristics of SE. Amniocentesis revealed normal karyotype and the couple chose pregnancy termination after our disclosure about the possible poor postnatal prognosis of the entity. Conclusion: The diagnosis of fetal HPE and its subtypes is important to determine prognosis and proper parental counselling. As in our case, multidisciplinary approach should be performed for the accuracy of the diagnose and fetal brain MRI may play an important role in more subtle cases.