Primary mesenteric liposarcoma is a rare soft tissue malignant neoplasm. The authors present a case of a 42-year-old male with pain in the abdomen and abdominal mass which showed a desmoid tumor on biopsy and CT shows a mesenteric mass present. The patient underwent exploratory laparotomy and a large tumor was excised. The specimen was sent for histopathology and showed dedifferentiated liposarcoma of the mesentery. Immunohistochemistry showed the tumor cells are diffusely positive for mouse double minute 2 (MDM2), p16, and show patchy positivity for the cluster of differentiation (CD) 34. The cells are negative for smooth muscle actin (SMA), desmin, S100, and ckit. After the surgery, the patient recovered well and was given adjuvant chemotherapy with doxorubicin, ifosfamide, and mesna. The patient has no signs or symptoms of recurrence to date. In this case, the combination of surgery and chemotherapy has shown to have a good clinical outcome.