Smokers may be at a greater risk of HIV infection, research suggests.
Smoking is also linked to other sexually transmitted infections
The UK researchers, writing in the journal Sexually Transmitted Infection, said tobacco smoke may increase people's vulnerability to infections.
However, they also found smoking tobacco did not appear to speed the progression of HIV to Aids.
The team, which reviewed previous studies, said the increased HIV risk could be because smokers were more likely to take sexual risks.
Dr Andrew Furber, a consultant in public health from the South East Sheffield Primary Care Trust and lead author of the paper, said: "We know tobacco can enter the bloodstream and affects the immune system."
He said studies have already shown that tobacco is linked to an increased risk in sexually transmitted infections, but his latest analysis reveals a link to HIV.
Out of about 3,500 studies, six looked into tobacco and HIV.
Dr Furber said five of these papers revealed that smoking increased the risk of acquiring HIV - smokers were between 60-300% more likely to acquire HIV compared with non-smokers.
But Dr Furber also added a note of caution. He said the increase could be caused by the fact that smokers could be more likely to take risks, such as unsafe sex, than non-smokers.
A review of the smoking and progression of HIV to Aids revealed no association.
But Dr Furber said a link could have been hidden by the fact that antiretroviral drugs, which slow the onset of Aids, were not in use at the time of the research.
Dr Furber said: "More research clearly needs to be done in this area. As the tobacco market is squeezed in the developed world, the tobacco industry increasingly looks to Asia, Eastern Europe and Africa.
"And these are the places where the HIV epidemic is at its greatest.
"So if there is this interaction, it is important to know about, because it could affect the way we run public health programmes in developing countries."
Keith Alcorn, a senior editor at the National Aids Map, said: "The weakness of this analysis, as the authors themselves acknowledge, is that most of the studies reviewed were carried out before the widespread use of antiretroviral therapy in developed countries.
"Earlier this year, a large US study in HIV-positive women found that smokers had a 36% greater risk of developing an Aids-related illness over five years of follow-up, despite taking potent antiretroviral therapy.
"Anyone living with HIV would be strongly advised by their doctor to stop smoking because of the increased risk of cardiovascular disease and the much greater risk of various smoking-related cancers for HIV-positive people, whether on treatment or not."