Ultrasonic examination of early pregnancies can lead to the discovery of vanishing twins. The main reason for such an evaluation is bleeding in the first trimester. Three women came to the emergency room of a community hospital with pelvic cramps and significant uterine bleeding containing clots. In two cases the cervix was soft and dilated, but in no case was the uterus smaller than was appropriate for the gestational age. Ultrasonic evaluation revealed a set of twins in all three patients. Patient 1 experienced early disappearance of a gestational sac (before ten weeks). Ultrasound demonstrated a blighted ovum in patient 2 until the 24th week of pregnancy. Macroscopic examination of patient 2's placenta at the birth of a normal, term, singleton infant revealed a compressed gestational sac. Patient 3 had developed a fetus papyraceous of 26 weeks' gestational size along with a normal singleton pregnancy. The only apparent complication associated with disappearance of a twin was first-trimester bleeding. Apparently a vanishing twin need not adversely affect the development of a coexisting singleton pregnancy. Therapeutic dilation and curettage for threatened or inevitable abortion should be avoided until a sonogram rules out the presence of a potentially surviving twin.