Objective The aim of our study was to investigate the normal cortical sulcus development in fetuses without central nervous system abnormality with transabdominal ultrasonography. Methods Our study was planned as a cross-sectional study in our clinic between November 2011 and October 2012. The study group was selected among pregnant women who applied to our hospital for routine antenatal follow-up. Singleton pregnancies, between 15th and 32nd gestational weeks, were included in the study. During the routine fetal ultrasonographic examination of these pregnant women, sylvian sulcus, parietooccipital sulcus, calcarine sulcus, and cingulate sulcus length measurements were taken and the correlation of these values with gestational week was evaluated. Results Three hundred and thirty-two patients were included in the study. Sylvian sulcus length, parietooccipital sulcus length, calcarine sulcus length, and cingulate sulcus length could be first measured respectively, at 15th, 17th, 17th and 25th gestational week. We found a positive correlation between gestational age and sylvian sulcus, parietooccipital sulcus, calcarine sulcus, and cingulate sulcus length measurements (p < 0.001). Conclusion Sulcal development and cortical maturation can be evaluated prenatally with transabdominal ultrasonography of the central nervous system.