Paedophile Victorian priest Frank Klep has been sentenced to 10 and a half years in prison for sex offences.

Klep taught at Salesian College Rupertswood in Sunbury, north of Melbourne, in the 1970s and '80s.

He pleaded guilty to 15 sex offences involving many boys, including siblings at the school aged between 11 and 15.

The court heard Klep was in charge of the school's sick bay and abused the boys when they came to him unwell.

Judge Frank Gucciardo described the 70-year-old's conduct as appalling, predatory and vile, and said it had created devastating lifelong consequences for Klep's victims and their families.

At one point the judge appeared to choke up while reading the sentence and had to leave the courtroom.

The court heard the parents of many victims did not believe them at the time, and Klep went on to preside over many weddings and funerals associated with those he had abused.

The mother of one victim, who did believe her son, wrote in her victim impact statement that she had been haunted by her decision to send her child to the school.

Young abused men left 'broken': judge

Judge Gucciardo described the boys as being in a vulnerable situation at the boarding school.

"Young men you abused were broken by your conduct," Judge Gucciardo told Klep.

"You've ruined lives and the ripple effect has touched every aspect of these young boys, and their families as well."

The judge said the abuse had stunted and damaged the victims' ability to have and keep relationships, and make the most of educational and employment opportunities.

He described the psychological impact as "devastating", and Klep's abuse of his power "reprehensible".

Klep was born in the Netherlands and migrated to Australia when he was 10 years old.

The court heard he had a happy childhood and was never abused.

Klep tried to apologise to victims involved in this case in court earlier this year but they walked out.

Many were in court when the sentence was handed down, along with members of Klep's family, who have continued to support him.

Klep has already served time in prison for other offences and will be eligible for parole in six and a half years.