Bernie Ebbers, the former chief executive of bankrupt telecoms firm WorldCom, has pleaded not guilty to criminal charges.
Bernie Ebbers after his court appearance
Mr Ebbers entered his plea during a brief appearance at Oklahoma district county court, before being released on $50,000 bail.
Last week Oklahoma state attorney general Drew Edmondson filed criminal charges against WorldCom - which has since been renamed MCI - Bernie Ebbers and five other former top executives.
The complaint accused the telecoms company and the former executives of breaking state laws by giving false information to investors.
WorldCom filed for the US' largest bankruptcy in July 2002 following an accounting scandal which is now thought to have reached $11bn.
The 15-count complaint by Oklahoma marked the first time Mr Ebbers had faced criminal charges.
Reid Weingarten, a lawyer for Mr Ebbers, said the charges contained no specific evidence of wrongdoing by the former chief executive.
"We know of no evidence whatsoever which links Bernie Ebbers to securities fraud," he said.
"Bernie Ebbers has committed no crime."
The next hearing in the case is scheduled for October.
MCI - as WorldCom is now called - has said it will cooperate fully with the Oklahoma attorney general.
It also said that it did not expect the charges to affect its emergence from bankruptcy.
A hearing to judge its reorganisation plan is due to take place next week.
But there was another blow for MCI on Tuesday, when it was sued by rival telecoms firm AT&T in a row over call routing.
The lawsuit accused MCI and a regional telecoms group Onvoy of routing calls through Canada, forcing AT&T to pay expensive connection fees.