Rent prices could rise by more than 24% in the next two years, according to a new study by estate agents Savills.
The report into the country's private rental sector found that the supply of rental properties had actually increased in the past five years - contrary to some assumptions.
However that growth had been completely outpaced by the rise in demand that had come due to fewer people being able to buy properties, as well as the increased use of private rental properties for social housing.
Savills said there were more than 100,000 additional people in rented accommodation now than in early 2011, with more than 18% of the population nationwide now renting.
In Dublin alone the report noted a 48.6% increase in the number of renters since 2011, with nearly one in four people (or 24.5%) there living in rented accommodation. This compared to 27% in London.
This has left the vacancy rate at around 1.5% nationally, which in turn has fuelled the sharp rise in rental prices.
"With rents back to boom-time levels, income yields on residential property are much more attractive than the returns that are available to investors who leave their money in the bank or buy a bond," commented Savills Director of Research Dr John McCartney.
Dr McCartney said that house price inflation, sluggish wage growth, weakened household balance sheets and tight mortgage lending have conspired to drive people who would otherwise have been owner-occupiers into the rented market.
"At the same time social housing tenants are increasingly being housed in private rented accommodation. This has driven a huge increase in rental demand," he added.
Today's report also suggested that a 300% increase in vacant units was needed before rents would stabilise.