Six cases of simultaneous intra- and extra-uterine pregnancies are described by the authors. The rate of 1/5000 deliveries is considerably higher than described in the literature. The association of the two conditions is seldom thought of and has never been diagnosed before the extra-uterine pregnancy has ruptured. The initial picture seems to be that of an intra-uterine pregnancy with a threatened abortion in 83% of the cases. Only 33% of the intra-uterine pregnancies reached term. The prognosis could be improved if the doctor were to think of the possibility more often.