Composite lymphoma (CL) is a rare disease with 2 distinct lymphomas concurrently arising in a single patient with an estimated incidence of 1–4.7% of newly diagnosed lymphomas per year. CL most commonly involves 2 B-cell non-Hodgkin lymphomas (NHL) or a B-cell NHL with a Hodgkin lymphoma. Our case is unique in that it was a bilineage CL with both a T-cell and B-cell NHL, which has only been reported in a few case reports. A 49-year-old woman presented with several months of progressive cough, weight loss, dyspnea, and supraclavicular lymphadenopathy. Computed tomographic imaging done upon admission to the hospital found that she had extensive anterior and middle mediastinal lymphadenopathy as well as bilateral supraclavicular lymphadenopathy. The patient underwent an excisional biopsy on the supraclavicular lymph node and was found to have a composite lymphoma involving both a T-cell and B-cell NHL. Her final pathological diagnosis was peripheral T-cell lymphoma and lymphoplasmacytic lymphoma. The patient was found to have stage IIIB disease. Her HIV, hepatitis panel, and tuberculosis tests were all negative. She then underwent chemotherapy with dose-adjusted EPOCH-R (etoposide, prednisone, vincristine, cyclophosphamide, doxorubicin, and rituximab). The patient showed a complete response and was then referred to a bone marrow transplant center for an autologous hematopoietic stem cell transplant. CL is a rare disease composed of at least 2 distinct lymphomas concurrently arising in a single patient. Due to the complexity in having to treat multiple types of lymphoma simultaneously CL presents challenges with treatment and assessing prognosis.