Objective To define an evidence-based conclusion concerning ultrasound screening for fetal genital system malformations during pregnancy. Methods In order to assess whether or not ultrasound screening for fetal genital system malformations is effective and feasible, we searched The Cochrane Library (Issue 3, 2009), MEDLINE (1981 to 2009), ACP Journal Club (1991 to 2008), and BMJ Clinical Evidence (1999 to 2008) for systematic reviews, randomized controlled trials (RCTs), cohort studies, and controlled clinical trials. Results Five cohort studies and three crosssectional studies were retrieved. The results showed ultrasound screening detected fetal sex determination by the contour of the rump and the angle of the genital tubercle to a horizontal line through the lumbosacral skin surface in the first trimester. Scrotal size and penile length increases with gestational age for male fetuses, and by 32 weeks, bilateral testicular descent was observed in most cases. Ultrasonographic scans, fetal genetic studies, and hormonal assays of amniotic fluid can diagnosis certain diseases, fetal sex differentiation disorders, fetal endocrinal disorders, and chromosome abnormality. Conclusion The findings of this study should reassure physicians and parents alike that ultrasound screening is an reliable option for the prenatal diagnosis of fetal genital system malformations, but more randomized controlled trials are needed to further supply relevant evidence.