Almost 40% of men who have sex with men have never been tested for HIV or a sexually transmitted disease, an online survey has found.
The research into sexual habits showed men who were least likely to have had the test were young, living outside Dublin, did not identify as gay, were out to few or no one, or had low levels of education.
But out of those who were tested for sexually transmitted diseases in the previous year, just over a fifth had been newly diagnosed with an STI.
The data came from the Men who have Sex with Men Internet Survey and was published by the Health Service Executive and G ay Health Network at a conference on gay health in Dublin.
The research, which was carried out from March 1 to May 31 last year, found almost two thirds of men who had sex in the last 12 months met their most recent male partner via a smartphone app or website.
This is the largest survey of its kind and just under one third of the 3,090 men who answered were under 25, and just over a quarter were over 40.
Mick Quinlan, representing the Gay Health Network (GHN), said: “It is very valuable to have this information, to help the HSE and GHN to continue to plan activities and campaigns for men who have sex with men in Ireland.”
The report said there were strong associations between the use of individual drugs and history of testing for HIV.
Men who had previously tested positive for the virus were significantly more likely to use all drugs, except for cannabis and LSD.
Cocaine was used by 34% of HIV-positive gay men surveyed compared with 13% of the total.
Nine out of 10 men had sex with another man in the previous year and 14% had sex with a woman.
Just under a third said they had sex with one partner, and 61% had sex with one or more non-steady partner in the last year, and 40% of them did not use a condom for anal intercourse.
The HSE noted there were 244 diagnoses of HIV among gay men last year, compared with 184 in 2014, an increase of one third.
It also reported that there were 218 diagnoses of infectious syphilis among gay men, an increase of 56% on the previous year.
The study found that the majority of men, 79%, described themselves as gay, 13% as bisexual, 2% as straight or heterosexual, and 5% as other. Two thirds were out to all, or more than half, of the people who knew them.