Fetal intestinal tract abnormalities can be pregnancy complications at all maternal ages. There have been reports of ultrasound identification of these abnormalities, particularly of fetal intestinal obstructions. We report the first case to our knowledge of elevated levels of the intestinal isozyme, alkaline phosphatase, in the amniotic fluid and blood serum and also the presence of prealbumin in the amniotic fluid of a fetus with extensive intestinal distension and polyhydramnios. It was revealed that the alkaline phosphatase intestinal isozyme as well as protein electrophoresis for abnormal albumin bands in the amniotic fluid are valuable markers for the early diagnosis of the above-mentioned fetal abnormalities.