Background: Gigantomastia of pregnancy is a rare, severely debilitating condition characterized by massive enlargement of breasts and resulting in tissue necrosis, ulceration, infection, and, occasionally, hemorrhage. Typically, resolution of breast hypertrophy to near prepregnancy size occurs in the postpartum period. Treatment is controversial. Methods: The authors present a patient with gestational gigantomastia for whom nonoperative management failed and who subsequently required bilateral mastectomies. In addition, the authors performed a comprehensive review of reported cases and generated a treatment algorithm. Results: The patient tolerated the mastectomies well and went on to deliver a healthy child. Postpartum delayed breast reconstruction with tissue expansion and implant placement yielded good results. The literature review demonstrates that medical management has successfully avoided surgery during gestation in 39 percent of cases since 1968. However, 35 percent of patients eventually underwent breast reduction (12 percent) or mastectomy (88 percent) during pregnancy. Spontaneous or elective termination of the pregnancy accounted for 30 percent of outcomes. Patients who underwent breast reduction and then became pregnant had a 100 percent (four of four patients) chance of recurrence. Two women had mastectomy and subsequent pregnancies. One woman developed multiple small areas of recurrence that were surgically excised. The other woman had two additional pregnancies with no recurrence of symptoms. Conclusions: Medical therapies to manage gestational gigantomastia are inconsistent in outcome. Since some patients respond, these therapies are worth trying. However, if the patient and/or fetus are experiencing significant morbidity, then surgical intervention is warranted. Breast reduction or mastectomy with delayed reconstruction is the preferred procedure. If the mother is considering future pregnancies, mastectomy offers the lowest risk of recurrence.