The department of gynaecology and obstetrics of the University Hospital in Libreville carried out in the five years between 1984 and 1988 8,688 ultrasound examinations of which 1,234 (14.2%) were performed because an ectopic pregnancy was considered possible. 213 correct diagnoses (32.8%) were confirmed by laparotomy. 649 surgical procedures for ectopic pregnancy were carried out of which 228 (35%) were helped by the ultrasound examination. The diagnosis was made 138 times (60.5%) accurately and suspected 75 times (32.9%). On the other hand, diagnosis was wrong 15 times (6.6%). These false negatives are worrying: in 4 cases there was an intra-uterine pregnancy as well and in these cases the intra-uterine zygote gave a false sense of security for the diagnosis. The 11 other cases were false diagnoses of adnexal infections which were diagnosed correctly by laparoscopy or culdocentesis. There were also 27 false positive diagnoses mainly in tubo-ovarian infectious and rarely where an ovarian cyst or pedunculated fibroid had twisted or the pregnancy was developing in a blind hemi-uterus. The assessment of the results makes its possible to show that in 88.75% the procedure was valuable in making the diagnosis and in 98.5% was valuable for excluding the diagnosis. Since the sensitivity of the test is 93.4% and its specificity is 97.3% it follows that ultrasound examination should have a very important place in the diagnosis of ectopic pregnancy particularly because in our unit we cannot at present carry out biological tests (beta HCG estimations). The test is rapid, cheap and easy to perform (as long as one avoids the traps).(ABSTRACT TRUNCATED AT 250 WORDS)