In order to evaluate the effects of whey supplementation on plasma GSH levels, HIV-infected patients were treated with a 45 g daily dose of whey proteins for a period of six months. Supplementation with whey proteins persistently increased plasma glutathione levels in patients with advanced HIV-infection. The treatment was well tolerated. A larger long-term trial is clearly warranted to evaluate whether this positive influence on the glutathione metabolism translates into a more favorable course of the disease.