Even though adnexal masses are detected during pregnancy ranging from 1 to 81 to 1 in 2.500 pregnancies, only 3% of these are malignant. A Krukenberg tumor is an ovarian metastasis of a gastric tumor and accounts for 1-2% of all ovarian tumors. A 29-year-old woman, gravida 3, para 2, was referred to our unit at 20 weeks' gestation because of epigastric pain for the last one week. Her abdominal ultrasound revealed a singleton pregnancy, with fetal measurements compatible with 20 weeks of gestation. A solid mass of 12.8 cm by 12 cm localized posterior to the uterus extending to both adnexial regions was also detected. Under general anesthesia, a midline abdominal incision was made. During abdominal inspection the gravid uterus was the size appropriate for the current gestational week. A 12 cm by 13 cm mass originating from the right ovary was excised. Then, a 17 cm by 18 cm mass originating from the left ovary was excised. The final pathology report confirmed positive washing cytology and a metastastic adenocarcinoma of both ovaries. Three weeks later, the woman had a gastroscopic biopsy and the pathology report was of an adenocarcinoma of the stomach. Unfortunately, the woman was lost to follow-up.