Amniotic fluid acetylcholinesterase (ACHE) has been used to evaluate neural tube defects. It has also been detected in ventral wall defects. However, the role of ACHE to differentiate between omphalocele and gastroschisis has not been established. We examined amniotic fluid ACHE in 16 pregnancies complicated by gastroschisis and 8 by omphalocele. One ruptured omphalocele was excluded. ACHE was negative in all 7 omphaloceles and either positive or suspicious in all gastroschises (χ2 = 17.3, p < 0.0001). Amniotic fluid ACHE may be useful to differentiate between omphalocele and gastroschisis