BACKGROUND Krukenberg tumor is a rare metastatic tumor of the ovary with characteristic histopathological features known as signet-ring cells. It usually presents in women around 45 years of age, however, we present an uncommon case in a 38-year-old pregnant woman. We report this case because of the unusual findings, the uncommon presentation in this younger age bracket, its diagnostic challenge, and poor prognosis. CASE PRESENTATION We describe an unusual case of a young woman with a history of painful vaginal bleeding at 13 weeks of pregnancy and treated for abruptio placentae. In her routine prenatal visit at week 20 of pregnancy, she was found to have a uterine fundus greater than her gestational age and referred to the hospital to discard polyhydramnios. At her admission a pelvic ultrasound was performed with normal findings of a 25 weeks pregnancy, also showing bilateral enlarged ovaries with heterogeneous echogenicity. The MRI showed a left tumoral lesion with dimensions of 22.1 x 13.6 x 16.3 cm, with lobulated regular contours with displacement of peripheral structures and mild compression of the bladder, the left ureter, and the inferior vena cava. The lesion was heterogeneous with irregular borders. The patient was programmed for a cesarean section; during the operation, the abdominal cavity showed bilateral tumors compatible with MRI findings, the ovarian tumors were sent to pathology and the results showed poorly differentiated mucinous adenocarcinoma (WHO III) with extensive signet-ring cells, an indicative of Krukenberg tumor. CONCLUSION: The case presented is rare due to its presentation in a pregnant woman without identifiable risk factors for gastric cancer. The incidental finding suggests the pregnancy masked the clinical presentation of gastric cancer, and the rapid deterioration of the patient is consistent with the aggressiveness described in the literature. The limited descriptions of this neoplasm in our country and the torpid evolution of this case highlight the importance of further studies of this cancer in Mexico.