The decision by a three-judge Superior Court panel came barely two weeks after they heard oral arguments by Sandusky's lawyer and a state prosecutor.
Sandusky had argued his trial lawyers did not have sufficient time to prepare, a prosecutor made improper references to him not testifying on his own behalf and the judge mishandled jury instructions.
The state attorney general's office said the 45-count conviction should stand.
Sandusky, 69, is serving a 30- to 60-year prison sentence at a state prison in southwestern Pennsylvania. If he does not get the convictions overturned, he is likely to die in prison.
His lawyer says he plans to ask the state Supreme Court to review the case.
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