Metastasis to bone or synovial tissue in the distal extremity is a rare event for endometrial carcinoma. This case report involves a 76-year-old female with stage II endometrial cancer who developed persistent ankle pain after a transabdominal hysterectomy and bilateral salpingo-oophorectomy. Plain films were initially negative. An MRI several weeks later demonstrated an abnormality in the synovial tissue of the sinus tarsi and in the distal tibia. A bone scan revealed increased activity on both sides of the ankle joint. Soft-tissue biopsy of the sinus tarsi was positive for endometrial adenocarcinoma. This is the first reported case of sinus tarsi syndrome, a chronic pain condition in the sinus tarsi of the hindfoot, secondary to metastatic endometrial carcinoma.