Hey Dad! star Robert Hughes has lost his High Court challenge to child sex convictions.

Hughes, 68, has been in jail since 2014, when he was found guilty on 10 sexual and indecent assault charges over offences committed in the 1980s.

He was found not guilty of an 11th charge, and sentenced to at least six years in prison.

Suggestions Hughes had a tendency to engage opportunistically in sexual activities with young girls formed a key part of the case against him.

Hughes argued each accusation was too different to be regarded as a tendency under law.

But in a four to three ruling the High Court supported the evidence used in the conviction.

An earlier appeal to the New South Wales Court of Criminal Appeal failed, with the court rejecting the argument Hughes had suffered a miscarriage of justice.