In the wrongful-death suit, Donald and Rosemary Teeman allege their son, Brian, killed himself in 1983 because of the abuse by Monsignor Thomas J. O'Brien when the family was living in Independence, the Kansas City Star reported.
The Diocese of Kansas City-St. Joseph knew O'Brien was sexually abusing boys and covered up the abuse, the suit says.
The diocese and O'Brien, now retired, are named as defendants in the suit, filed in Jackson County Court Tuesday.
The parents said they didn't know about the abuse or the reason for Brian's suicide until a classmate called them two months ago and told them of the abuse. The classmate filed suit against O'Brien and the archdiocese last week.
The diocese issued a statement saying it "has not received the (Teeman's) lawsuit and cannot comment on the specifics of the allegations."
The first lawsuit alleging sexual abuse was filed against O'Brien in 2004 and he now faces more than two dozen sexual abuse suits, the diocese said.
Brian Teeman's sister, Jackie, said the family had long questioned why Brian shot himself at his home on Nov. 1, 1983.
"For 28 years we punished ourselves every day trying to come up with a reason for him to commit suicide," she said.
Details of the sexual abuse shared by the classmate "make us sick to our stomachs," she said.