Objective: To assess the role of brain magnetic resonance imaging (MRI) in fetusespresenting with isolated ventriculomegaly (IVM) in the ultrasound (US) evaluationof the fetal brain. Methods: US and MRI findings of 197 fetuses diagnosed withIVM between November 2018 and November 2020 were retrospectively evaluated.Fetuses with abnormal karyotypes, additional anomalies, or known etiologies forventriculomegaly were excluded. US and MRI findings were compared both in termsof mean ventricular measurements and IVM grade. Results: MRI measurementswere significantly higher in mild IMV (10.33 ± 0.38 mm vs. 11.11 ± 0.51 mm, p<0.001) compared to US. In mild IVM, MRI measured ventricles larger than US witha mean difference of 0.78 mm. There was no significant difference in US and MRImeasurements in terms of mean values in moderate and severe IVM. There wasgood agreement between US and MRI in d...