Sonohysterography is a technique in which fluid is instilled into the uterine cavity to enhance endometrial visualization during transvaginal sonography. It allows more accurate delineation of various intracavitary, endometrial, and submucosal myometrial pathologies, thus enables to reliably distinguish focal from diffuse endometrial abnormalities and differentiate endometrial from myometrial abnormalities. Indications for sonohysterography include abnormal uterine bleeding, infertility, intracavitary endometrial or myometrial abnormalities, and detected or suboptimally imaged endometrium by transvaginal sonography. This technique is simple and well tolerated, and has a low rate of complications and few limitations. In this chapter, sonohysterographic appearances of the common pathologic conditions are illustrated in detail: endometrial polyps, submucosal leiomyomas, endometrial hyperplasia, endometrial intraepithelial neoplasia, endometrial carcinomas, tamoxifen-related changes, other polypoid endometrial and myometrial tumors, intrauterine adhesions, other miscellaneous pathologic conditions, including endometrial calcifications and metaplasia, endometritis, placental polyp, uterine septum, and post-cesarean delivery niche. Potential pitfalls that can mimic pathology, as well as technical artifacts, are also shown.