The report, which was outed by SVT's Rapport news programme, interviewed 400 people and revealed one in two had been the victim of sexual abuse or rape.
The figures were unexpected according to Göran Johansson, who led the study.
“I hadn't anticipated the extent of the problem or the number of foster children exposed to such abuse," he told SVT.
The investigation was set up to survey how children from the 1920s to the 1990s experienced their childhood in society's care.
”We also have serious examples of how perpetrators were protected rather than the children's stories being heard,” Johansson added.
An initial report was submitted at the beginning of the year and the survey will continue into 2011, aiming to hear evidence from 1,000 interviewees in total.
Following the completion of the investigation the government is expected to consider its position in regard to requests for damages.