Massive Ovarian Edema (MOE) is a rare cause of ovarian enlargement. Only 77 cases have been reported in the world literature so far, merely three of which were observed during pregnancy. Two of these showed additional pathological changes of the affected ovary (torsion) or were found in twin pregnancy. The patient presented on hand is therefore only the second report of MOE in an uncomplicated singleton pregnancy. In this case, a therapeutical resection of the affected ovary was performed at 16 + 4 weeks of gestation. The further course of the pregnancy was uncomplicated.