The diagnosis of ectopic pregnancy is clinically difficult. To determine how the different sonographic patterns help in making the diagnosis of ectopic pregnancy, the ultrasound examinations of twenty-three patients were retrospectively reviewed. Four sonographic types of ectopic pregnancy were found: Type 1--Cystic adnexal mass with a fetal pole. Type 2--Cystic adnexal mass with no fetal pole. Type 3--Complex or solid adnexal mass. Type 4--Pelvis fluid with no mass. In Type 1, a specific ultrasound diagnosis of ectopic pregnancy could be made. In Types 2, 3 and 4 the sonographic findings although suggestive of an ectopic pregnancy were not specific. In these cases the diagnostic accuracy was increased if culdocentesis was performed when ultrasound demonstrated fluid in the pelvis. Unlike previous reports, uterine size, endometrial echoes and myometrial echoes were found to be of no value in making the diagnosis. The positive pregnancy test increased the diagnostic specificity of the ultrasound examination. Even if the pelvic sonogram was normal, an ectopic pregnancy could not be excluded if the pregnancy test was positive.