We describe the prognostic implication and aggressive clinical course of lymphoma-related lactic acidosis in a rare HIV-related lymphoma. Patient was diagnosed with plasmablastic lymphoma and developed severe lactic acidosis, and was treated on the medical floor and in the medical intensive care unit. Her lactic acidosis was considered to be type B, secondary to her underlying lymphoma since she never had an infectious source, hypovolemic state, or low/high cardiac-output state. The mechanism of the lymphoma-related lactic acidosis is from altered cellular metabolism, thought to aid in lymphoma proliferation, rather than tissue hypoperfusion. It is a rare complication of aggressive lymphomas and signifies a poor prognosis. Patients having this complication should be considered for close monitoring and management in an intensive care unit until definitive treatment (i.e., chemotherapy) can be implemented.