In the first six months of this year the number of new cases has increased by 40 percent, compared to the same period last year.
The majority of those infected are heterosexual.
In the first half of 2007, 252 new cases of HIV were reported to the institute, the highest half-year figure since reporting began 20 years ago. According to a spokesperson from the institute, the number of cases in all categories - heterosexual, homosexual and intravenous transmission - have risen, and this may, in part, be explained by immigration trends.
A little over half of the cases in Sweden were people who had moved here from other countries, and 70% of HIV positive heterosexuals had been infected prior to arriving in Sweden.
The institute believes that fewer people are practising safe sex, as witnessed both by these findings and the increase in cases of chlamydia, another sexually transmitted disease. A lack of public awareness of the disease is also being blamed for the rise in HIV.
There are currently a total of some 7,700 people in Sweden who are reported as carrying the HIV virus.