Pelvic masses in pregnant women are rare. However, the incidence of pelvic masses is likely to increase due to the combination of the delay in childbearing and the routine practice of ultrasound during pregnancy follow-up. Pelvic masses can have a gynecological or nongynecological origin. Gynecological pelvic masses can originate in the adnexa or the uterus, mainly in the form of adnexal cysts or myomas. Most pelvic masses are asymptomatic, and diagnosed incidentally during routine first-trimester ultrasound. When symptoms are present, the most common one is abdominal pain. The aim of this chapter is to summarize the published literature on gynecological pelvic masses in pregnant women, focusing on adnexal cysts and myomas, as well as the possible symptoms, complications, and treatment.