During the past eight years ultra-sound scans were carried out on 281 patients with the suspicion of ectopic pregnancy. Diagnostic criteria were established which were designed to minimize false negative results. In 52 cases the clinical suspicion was confirmed by operation. In 46 of these patients ultra-sound signs of ectopic pregnancy were present. Six ectopic pregnancies were not recognized by ultra-sonographies. 73 patients were suspicious of ectopic pregnancy but did not show ectopic pregnancy. The high rate of ultra-sound misinterpretation in ectopic pregnancy is due to the variability of ectopic pregnancy, abortions of intra-uterine pregnancies, abnormalities of the uterus, and adnexal tumours of other etiology. Negative ultra-sound findings do not rule out an ectopic pregnancy since a number of cases with the clinical suspicion of ectopic pregnancy show intact intra-uterine pregnancies. Ultrasonography is a valuable additional diagnostic method in suspected cases of ectopic pregnancy.