Objective: To describe a new first-trimester sonographic landmark the maxillo-occipital line which may be useful for early screening of open spina bifida. Methods: Maxillo-occipital line was prospectively evaluated in 100 low risk pregnancies at the time of first trimester sonographic screening examination between 11 and 13_⁺⁶ weeks" gestation. All the pregnant women subsequently had a normal second trimester scan and normal outcomes. Mid-sagittal brain images of 14 fetuses with known diagnosis of open spina bifida were evaluated retrospectively to review the maxillo-occipital line. Results: None of the 100 fetuses evaluated prospectively with the maxillo-occipital line below the junction of the midbrain and brain stem were affected by open spina bifida. The aqueduct of Silvius to occiput distance measurement was not obtained in 5 cases. In all, 14 cases with a diagnosis of open spina bifida, the junction between the midbrain and brain stem, were below the maxilla-occipital line. Conclusion: Maxillo-occipital line is an easy addition to the evaluation of first trimester screening of open spina bifida. Further studies are needed to determine the false-positive and false-negative rates of this technique.