INTRODUCTION We describe a case of conservatively treated endometrial endometrioid (EE) adenocarcinoma which showed an aggressive clinical outcome after pregnancy. CASE A 30-year-old woman with a well differentiated EE adenocarcinoma decided to attempt a conservative approach and underwent progestin treatment with subsequent negative ultrasound and hysteroscopic controls. After 3 months, she conceived and at 36 weeks of gestation, a cesarean section was performed with multiple negative biopsies. Eight 8 months after delivery, an exploratory laparotomy documented disseminated poorly differentiated EE adenocarcinoma. Staging work up revealed diffuse metastatic disease. Despite chemotherapy, the patient experienced progression of disease with fatal acute respiratory syndrome due to massive neoplastic pulmonary lymphangitis. CONCLUSION Conservative medical management of endometrial cancer in young women willing to preserve their reproductive potential, carries on potential risks. Careful selection of cases, informed consent, and strict follow up procedures are mandatory.