Fetal acrania is uniformly lethal and termination is suggested whenever the diagnosis is made. Traditionally, the diagnostic tool was 2-D ultrasound (US). In this series, we report our work of detecting acrania using 3-D US. We reviewed our medical records of prenatal diagnosis on fetal acrania in National Cheng Kung University Hospital from May 1997 to December 2002. All the cases were scanned by a 3-D US scanner. In total, 29 cases of fetal acrania were diagnosed. The range of gestational age at prenatal diagnosis by US was between 11 and 21 weeks and 44% were depicted in the first trimester. Among them, 93.1% were isolated findings, and one was associated with trisomy 18. Comparing with previous literature, 3-D US can detect fetal acrania as early as 2-D US, and it also can provide additional vivid illustration after various modes of reconstruction, which 2-D US cannot. In conclusion, 3-D US may contribute to early detection of fetal acrania and provide a novel visual depiction of this defect after reconstruction; thus, assists substantially in diagnosis as well as consultation.