A thirty-year old HIV-positive woman, who had been receiving antiretroviral therapy (protease inhibitor, lamivudine and stavudine) for seven months, was diagnosed with severe lactic acidosis type B, most likely induced by nucleoside reverse transcriptase inhibitor treatment. The antiretroviral therapy was ceased, and she was treated with isotonic sodium bicarbonate intravenously. She made a full recovery apart from a perceptive hearing deficit.