A 36-year-old HIV positive (HIV RNA: 6000 copies/ml, CD4 cell count: 359/ml), obese (body-mass-index: 40.9), therapy-naïve female patient, who after 7 months of well tolerated and effective antiretroviral therapy (stavudine, didanosine, efavirenz), had slight gastrointestinal discomfort and suddenly developed a lactic acidosis (arterial-pH 7.03 [7.36 Á/7.44 She died 4 days later despite intensive care (continuous venovenous haemodiafiltration, sodium-bicarbonate infusion, high doses of vitamins, respiration).