Twelve hundred disputes between landlords and tenants were reported to the Private Residential Tenancies Board last year, according to the body's latest annual report.
The figure is up from 900 in 2005 and the PRTB says the majority of disputes arose from landlords keeping deposits when tenants moved out of rented accommodation.
Elsewhere, the board's annual report says the number of registered tenancies in 2006 was 138,000, up from 84,000 in 2005.