Gigantomastia (macromastia, hypermastia) is a rare disease associated with excessive hypertrophy of the connective tissue of the breast in women. Gestational gigantomastia is a type of disease, the most common type. It develops during pregnancy under the influence of hormonal surges of progesterone, prolactin, and estradiol. More often, gigantomastia is bilateral, less often-unilateral. The disease occurs in one case per 28000-100000 pregnancies. As a rule, the condition develops in the first trimester under the influence of placental hormones. The consequences of the disease are more often observed in women with multiple pregnancies. Approximately 150 cases of gestational gigantomastia have been reported. After childbirth, in some cases, the breasts return to their postpartum state, but with subsequent pregnancy they increase again, usually more significantly. The condition threatens the health of the mother, but has a good outcome for the fetus. Despite the benign nature of gigantomastia, it can cause a dangerous condition and even death from severe infection and cardiopulmonary failure. This article describes a rare clinical case of gestational gigantomastia. Taking into account the optimal chosen management tactics of the patient, a relatively favorable outcome of pregnancy and childbirth for the mother and fetus was obtained.