The highest number of new HIV cases was recorded last year, according to the latest official statistics.
The figures from the Department of Health show 209 cases, an increase of 73 from the 1998 figure.
A spokesman for the Department said it was "concerned" at the increase and was finalising a new strategy to deal with it.
Of the 209 new cases recorded, 120 were men, 81 were women and in eight cases the gender was not recorded.
A total of 140 of the new HIV cases were people under the age of 35. Most new cases were in the Dublin area, with 161 recorded by the Eastern Health Board.
The biggest single category of new HIV cases recorded was drug users, with 69 new cases.
This compared with only 26 drug users recorded as contracting HIV in 1998.
The number of heterosexuals who contracted the disease in 1999 was 59, compared to 47 in 1998.
The 1999 figures also show that 40 homosexuals, 23 "children at risk" and 13 prisoners contracted HIV.
Two hospital staff were also recorded by the Department as having contracted HIV, as were one haemophiliac contact, one blood donor and one organ donor.
Dr Fiona Mulcahy, consultant in genitourinary medicine at St James's Hospital - which is one of the main centres handling new HIV cases - said the trend appeared to be continuing this year.
She said the hospital's records showed 71 new cases for the first four months of 2000.
The clinic at St James's was "absolutely swamped" because of the increase in HIV cases.
Dr Mulcahy said there were a number of reasons for the increase. One factor was a rise in the number of young people contracting the disease.
"There is a new cohort of people who know each other and pass the disease from one to another." A large proportion of the new cases were people aged between 17 and 21.
She said the increase of HIV cases in heterosexuals was also related to the increase in the number being screened, such as pre-natal screening.
She said immigration was also a factor; some 21 per cent of the new cases recorded at St James's Hospital this year to April were immigrants.
According to Mr Paddy Connolly, of the HIV/AIDS support group, Cairde, a lack of understanding and prejudice were the most significant factors in the increase of HIV.
"They have a knock-on effect as to whether people will come forward for testing, whether they'll tell their family," he said.
Cairde will today publish its own strategy report which Mr Connolly said would show how involving more Government departments - particularly the Department of Education - could more effectively address prevention and the needs of those affected by HIV and AIDS.
"If other Government departments [than Health] were involved, people might view it as a broader issue," Mr Connolly said.