This paper reviews the various examination techniques, the clinical indications, and the imaging findings for US studies of the female pelvis in patients with gynecological problems. Ultrasound, in fact, is the preferred imaging modality in the study of the female pelvis, and provides information of basic importance in detecting and characterizing pelvic masses of uterine, ovarian, or adnexal origin, providing also criteria useful in predicting their benign vs malignant nature. In patients with abnormal bleeding, transvaginal US helps in determining the presence of morphological and structural changes of the endometrium and, with the use of sonohysterography, provides excellent delineation of the endometrial cavity, guiding appropriate planning of therapeutic procedures. Ultrasound plays a very important role in the evaluation of patients with acute pelvic pain. It allows identification of ovarian torsion and has both diagnostic and therapeutic capabilities in patients with pelvic inflammatory disease through guidance of abscess drainage via the transvaginal route. In suspected ectopic pregnancy, US, together with quantitative measurements of hCG levels, can be considered the best imaging procedure to guide to the diagnosis. Ultrasound has an important role also in the study of female infertility. In this field it can be used to identify and document the integrity of the reproductive tract as a conduit for the passage of gametes and embryos, to detect pathological changes that may be causes or contributing factors of female infertility, to monitor cyclic changes of pelvic organs to document normal physiology or pathological situations, and to guide infertility treatment.