At first, I thought that Paul might be wearing an oddly knit undershirt, full of holes that my arm and fingers sensed as they pushed against his back. But when I removed his vest and pulled his shirt up, I saw that the holes bore through his skin. Dozens of irregular wounds, some weeping pus, spread across his shoulders. I stopped my exam and laid Paul back on the bed. I turned his face to mine and asked: "Paul, what are these holes?"

From the despair in his eyes, I immediately understood why the holes were there. We cleaned and dressed his wounds, and gave him fluids. Later, when Paul regained sufficient strength to explain, he told me that the holes had been caused by chemical compounds containing DMSO (dimethylsulfoxide), a worthless solvent that was supposed to draw out the human immunodeficiency virus from his body. He died a few days later.

As a physician who directed an AIDS ward during the early years of the epidemic, I remember scores of young men and women with AIDS whose dark, hollow eyes, vacated of hope, looked into mine. Many of these patients clutched talismen: magical herbs imported from Brazil or boxes of mysterious compounds concocted by local "underground labs." You do not forget those looks. They are the desperate, haunting looks of dying people who want, however obliquely, to see what they know does not exist. These young men and women died with compound Q in their pockets, AL-721 in jars, Iscador on the nightstand, hypericin (St. John's wort) under the bed -- old medicines that had proved virtually powerless against the disease that had overrun their bodies. They died with newspaper clippings announcing the coming of a new drug called AZT taped to their walls or tucked under their pillows.

I remember how the world changed when AZT arrived. It was a potentially toxic drug, but it brought the first real light of hope back into people's eyes. It had demonstrable activity against HIV, and, most important, some AIDS patients who took AZT actually got better. You could literally watch skeletal bodies flesh out to three-dimensional forms. In conjunction with therapies that helped prevent other infections, for the first time, patients began to live a little longer than the nine-to-11-month life span to which they had been destined before. Other drugs active against the retrovirus HIV (anti-retroviral therapies, or ARTs) were developed later and shown to prolong human survival and make people healthier. It was these drugs that so many of my now-dead patients had been hoping for during the 1980s. They wanted the chance to have more of their lives. Many would have opted for anti-retroviral therapy and some would have lived a lot longer.

But if the "HIV deniers" had their way, such powerful therapies would not be available today. These vocal dissidents insist that HIV does not exist, charging that the drugs that have been developed to combat it are part of a massive medical hoax propagated by a greedy pharmaceutical industry, a lockstep scientific community and a vapid media machine. In their view, AIDS is not a contagious disease at all, and so ARTs are toxic, if not downright evil, and safe sex is irrelevant. In my most generous moments, I understand their erroneous thinking as a byproduct of fear and anger about HIV, a lack of experience with the human history of AIDS and the usual anti-establishment sentiments. But, most of the time, what I see is that the cost of their rhetoric is an unknowable number of lives that could be lost because of it.

While most HIV deniers (who are mostly white Americans) neither give care to people with AIDS nor conduct HIV research, they do spend a considerable amount of time building a political base. For many years their ideas have languished in the margins of both the scientific and activist communities, but this summer they got a boost when South African President Thabo Mbeki allowed the work of famed HIV denier and University of California at Berkeley professor Peter Duesberg to be incorporated into this month's 13th International AIDS Conference in South Africa. Duesberg, whose AIDS research has been criticized by most AIDS researchers, has consistently maintained that HIV does not cause AIDS. He cites as evidence the failure of HIV to comply with specific scientific postulates (the "Koch postulates," created in 1840 and 1890, before the discovery of viruses) or to follow cardinal rules of virus behavior. Rather, Duesberg and the deniers believe that AIDS is caused by chromosomal damage, certain lifestyles, drug abuse, malnutrition, poor sanitation and parasitic infections.

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