It appears that maternal indomethacin therapy may be a useful adjunct in selected cases of polyhydramnios. Initial evaluation should include glucose tolerance testing and a thorough search for fetal abnormalities by ultrasonography. In the patient with symptoms such as premature labor or respiratory compromise, an initial amniocentesis should be considered for decompression and fetal karotype. Oral indomethacin therapy can then be started. Although the optimal dose is unknown, a 25-mg oral dose every 6 hours appears adequate. Ultrasound assessment of amniotic fluid volume should be done once or twice weekly. If oligohydramnios develops, the indomethacin should be discontinued, and the amniotic fluid volume serially monitored. Fetal echocardiography should be considered in the first 24 hours after therapy has been initiated and weekly thereafter. Evidence of severe constriction of the ductus arteriosus or tricuspid regurgitation warrants discontinuation of the indomethacin; lesser degrees of ductal constriction can be treated by decreasing the dose of the medication.