An unusual case of extramembranous development of 1 infant in a twin pregnancy is described. The pregnancy was associated with the intermittent loss of liquor and a bloody discharge starting at the 26th week of gestation. Spontaneous delivery occurred at the 32nd week of gestation; the first infant was delivered by vertex and the second by breech presentation. The first infant was normal, but the second infant, who died shortly after delivery, had most of the external features of dysplasia renofacialis. (Potter facies). The gestation was diamniotic, dichorionic, and with a single placenta, but the side of the affected twin was markedly circumvallate, with short, thick membranes that covered no more than 10% of the infant.