Until now the indication for hysteroscopic metroplasty has been based on laparoscopic findings and thus depended on the operator's experience. Using ultrasound and magnetic resonance images of double uteri it should be possible to find more objective indications for this operation. When three points are identified on longitudinal scans of the uterine fundus, the two tubal ostia and the mid-point of the fundal perimetrium, hysteroscopic metroplasty is indicated only in uteri in which the third point is at least 5 mm above a straight line drawn between the tubal ostia. This classification criterion includes more cases than laparoscopic criteria in this study; we performed hysteroscopic metroplasty in 23 double uteri and had we followed the laparoscopic criteria the operation would have been performed only in 19.