Accident Compensation Corporation (ACC) figures released under the Official Information Act reveal between 2011 and 2013 there were was a 29% increase for claims involving inflatables, such as bouncy castles and bungee runs, in Otago, and a 75% increase in Southland.
In Otago, 27 claims involving inflatables structures were lodged in 2011 and another 35 claims were lodged last year.
In Southland, the claims ballooned from eight claims in 2011 to 14 claims last year.
Nationally, claims jumped 38% - from 616 claims in 2011 to 851 claims last year.
Some of the accident claims described falling awkwardly, rolling ankles, jarring backs, twisting knees, getting a toe caught, and a sister landing on their arm.
Another person injured described what happened on an inflatable obstacle course.
''I jumped over on obstacle and hit my face on my own knee.''
Video Tech owner Mervyn Wilson, of Dunedin, said he had been hiring out inflatable structures in Dunedin for more than 25 years.
He had 30 inflatables - mostly castles - for hire.
Most bouncy castles were designed to handle the force of a child's weight - not an adults - but that did not stop adults trying to hire them for their own use.
Students in Dunedin wanted castles for welcome-back parties at their flats, he said.
The requests were declined because the mix of a bouncy castle, adults and alcohol was an accident waiting to happen, Mr Wilson said.
The ACC figures revealed more older people hurting themselves on the inflatables.
In 2011, the oldest person to injure themselves in Otago was aged between 45 and 49, and in Southland was aged between 15 and 19.
Last year, the oldest person to injure themselves in Otago was aged between 55 and 59 and in Southland between 65 and 69.
In New Zealand, someone aged 85 years and older was injured on an inflatable in 2011 and 2013.
Mr Wilson said there were more ''substandard'' bouncy castles for sale in New Zealand, made from lightweight nylon material.
The commercial canvas castles he bought for hire were heavier, more durable and treated with fire retardant.
A Worksafe New Zealand spokesman said Worksafe was investigating the case of an 8-year-old boy falling from a bouncy castle at Pisa Range Lake Resort last month.
