A former senior policeman has said abuse at Rubane House in County Down was 'rampant'.
The home was run by the De La Salle religious order, and the Historical Institutional Abuse (HIA) inquiry was told it was the subject of a police investigation in the 1990s.
Three order brothers were charged, but legal issues meant none were convicted.
It is thought the abuse could be on a scale similar to, if not worse than, the abuse at the notorious Kincora Boys' Home in east Belfast.
Former Royal Ulster Constabulary detective chief superintendent Eric Anderson wrote a note to the director of public prosecutions (DPP).
It said: "Sexual abuse by a considerable number of the De La Salle brothers on the children and consequently between children is rampant.
"The full horror of the abuse in this establishment is reflected in 41 files already submitted through your office to the DPP.
"I consider the complaints made to show it to be on a par with, if not worse than, the abuse at the Kincora children's home."
Three senior staff at Kincora were jailed in 1981 for abusing 11 boys in their care after a scandal in the 1980s.
Rubane housed around 1,000 children between 1951 and 1985, and it has been alleged that 200 were abused.
Fifty-five have come forward for the inquiry and most of these will give evidence.
The inquiry is expected to begin next month.