Fetal swallowing and voiding were measured using colloidal Au and an ultrasonic scanner, respectively. Subjects were in their 38-40th wk of pregnancy. Cases were divided into 3 groups: normal, hydramnios and oligohydramnios. The normal group had a mean swallowing rate of 198 ml/day and a mean voiding rate of 23.6 ml/h. No significant differences were found among these rates and the corresponding rates in the other 2 groups. Mechanisms other than fetal swallowing and voiding can contribute to the control of amniotic fluid volume at term.