Acute polyhydramnios in monozygotic twin pregnancy causes severe maternal discomfort and carries a high risk of premature labor. During the years 1980 to 1987, 36 patients with this complication were delivered in Sweden, giving an incidence of 1/20,000 births, or 1/200 twin births. In 18 patients (group A) who were treated with one or more amniotic taps, the delivery was postponed by 2 weeks, as compared with one week in 18 conservatively treated patients (group B). the peri- and neonatal death rate was 47% in group A and 58% in group B. Our own experience is that amniotic taps are safe if the amniotic fluid is removed slowly under prophylactic tocolysis. It gives symptomatic relief to the mother and may postpone labor until the gestational age of the twins is more compatible with survival.