Background/aims: Gastric cancer in pregnancy is extremely rare and often diagnosed at advanced stages. Well-recognized pregnancy-related symptoms, such as nausea and epigastric discomfort, can be the first symptoms of gastric cancer. Thus, the diagnosis of gastric cancer in pregnancy is difficult. We herein report a case of gastric cancer in pregnancy to alert clinicians to this rare possibility. Materials and methods: A 22-year- old nulliparous woman was examined by a gynecologist with a complaint of low abdominal pain. An abdominal ultrasound of the patient revealed 7th week of gestation and also showed massive ascites. She was referred to a hospital for further evaluation. Her other symptoms included loss of appetite, early satiety, and postprandial fullness. Gastroscopy demonstrated a tumor originating from the cardia and invading throughout the distal corpus. The histopathological diagnosis was gastric carcinoma with signet ring cells and her pregnancy was terminated. An explorative laparotomy revealed an unresectable gastric cancer and multiple peritoneal implants. Tumoral invasion was detected in pancreas and spleen. She was admitted to the medical oncology clinic and received a palliative chemotherapy. Bilateral double-J-stent placement was performed because of obstructive uropathy. A nasogastric tube was inserted for intestinal decompression, and total parenteral nutrition was administered. An adequate pain medication was given. To date (3 months after the diagnosis) the patient has been well without any signs of progression. Conclusion: Early diagnosis of gastric cancer is very important for a better outcome. The diagnosis may be delayed because mild gastrointestinal symptoms are common during pregnancy. Clinicians should take this into consideration in the differential diagnosis of persistent epigastric complaint during pregnancy. Suspicion and early upper gastrointestinal endoscopy are necessary.