Objective: Ectrodactyly is a rare malformation with various presentations. The current report describes a case of ectrodactyly detected using 2-dimensional (2D) and 3-dimensional (3D) ultrasonography at 16 weeks’ gestation. Methods and Results: The 2D ultrasonographic findings were ectrodactyly in the right hand and monodactyly in the left hand, and these results were confirmed and further clarified using 3D imaging. The postmortem X-ray findings were consistent with the ultrasonography. Conclusion: We conclude that 3D ultrasonography can assist in clarifying 2D ultrasonography findings of hand malformations during the second trimester of pregnancy.