Chylothorax is a rare complication of advanced lymphoma. We present the case of an 80-year-old man diagnosed with B cell lymphoma presenting with a right chylothorax secondary to a large retroperitoneal mass. His disease was not responsive to initial treatment with chemotherapy. Fractionated radiotherapy to a dose of 2,000 cGy in five fractions was delivered to the retroperitoneal mass, and the chylothorax improved significantly within days of initiation of treatment.