The new board members are Nicholas Katzenbach and Dennis Beresford. Neither has previously been involved with WorldCom's business affairs, the company said.
As directors they will be appointed to a committee charged with conducting a review of the company's accounting practices and preparation of financial statements.
The new committee will oversee an investigation being led by William McLucas, former chief of the enforcement division of the US Securities and Exchange Commission, as announced by WorldCom in an open letter to US president George W Bush on 28 June.
Katzenbach, a private attorney, served as US Attorney General from 1965 to 1966, US Under Secretary of State from 1966 to 1969 and then as a senior vice-president of IBM until 1985.
Beresford is Professor of Accounting at the University of Georgia and served as chairman of the Financial Accounting Standards Board from 1987 to 1997.