The cost of renting a private property in Northern Ireland rose by 3.7% in the year to August, according to new figures.
The average rent here in August was £634 - up 2.3% from £625 in July. In August 2016 it was £610.
Across the UK rent grew by 2.4% over the year to August, the highest rate of growth in the sector this year, the HomeLet Rental Index found.
UK families are now paying out an average of £939 per month for accommodation.
HomeLet, which offers specialist rental insurance, said rents in London have reached their highest since the index launched in 2009.
Rents in the capital rose 2.5% in August following three months of decline, reaching an average of £1,609.
It is the first time rents in London have been above an average of £1,600.
The 2.4% rise across the UK is the highest rate of annual inflation since November 2016. The average monthly rent of £939 is £23 higher than August of last year.