There is no need any more to demonstrate the value of echotomography in the diagnosis of extra-uterine pregnancies. All the same, the authors want to point out in the light of two cases they have had the rare, but real risk of errors made because of deficiencies in echography, which because they have excluded extra-uterine pregnancy lead to a delay which can be considerable in diagnosis. The first section deals with the features of diagnosis to be considered in extra-uterine pregnancy (an empty uterine cavity or, on the other hand, the presence of a pregnancy sac in the uterus; rarely the picture of an ovum in an ectopic position, but more often the picture of a haematosalpinx or a haematocoele). The risks of making mistakes because of insufficient information are described. These mistakes can be of serious consequence because they delay using the laparoscope (particularly likely to occur if there is the presence of a pseudo-sac of pregnancy due to separation of the decidua). Finally, the risks of making mistakes by having too much information are spelt out. These are less serious because they do lead to the use of the laparoscope. (They are wrongly diagnosed ovarian cyst, hydrosalpinx and double uterus.) In the last section the statistics given by various authors are reviewed.