Ebbers cited his constitutional right not to testify on the advice of counsel. Nonetheless, he said, "I do not believe I have anything to hide."
He went on to say that when he gets the opportunity to explain his actions, "I believe no one will conclude that I engaged in any criminal or fraudulent conduct during my tenure at WorldCom."
Financial Services Committee chairman Michael Oxley called WorldCom's near-$4bn (£2.6bn) in inflated earnings a "betrayal" of public trust.
Oxley made clear what he thought the penalty should be for the company's alleged deception. "The consequences to this sort of criminal activity, should it be proved, should be severe and that may mean time in federal prison."
Others testifying - Melvin Dick, a former managing partner at Arthur Andersen, and Jack Grubman, a telecommunications analyst at Smith Barney - had to absorb the committee's fury.
Dick said his accounting firm had no inkling that billions in expenses were improperly booked as capital expenditures, and he said WorldCom's managers specifically denied to auditors that the books included "top side entries", a term describing unauthorised or questionable accounting.
"The fundamental premise of financial reporting is that the financial statements of a company are the responsibility of the company's management, not its outside auditors," said Dick.
Committee members greeted Dick's explanation with incredulity.
Grubman, who has covered WorldCom for many years, denied that he had any advance knowledge about WorldCom's earnings misstatements, and had been downgrading WorldCom's stock before last month's disclosure that the company had issued misleading financial disclosures.
He did, however, disclose at the hearing that he had attended WorldCom board meetings and had received "non-public" information a day or two in advance of its release. He denied any special relationship with the company's senior managers.
"I think I had a good working relationship with Mr Ebbers. I don't think I had a special relationship with the board," said Grubman.
Also scheduled to testify was John Sidgmore, the new president and CEO of WorldCom, who said last week that bankruptcy was possible for the company, as are more layoffs.