Inez McCormack and Professor Christine Bell wrote to Northern Secretary John Reid tendering their resignations with immediate effect.
They both expressed their long-standing concerns at the failure of the Commission to effectively promote and protect human rights as mandated by the Good Friday Agreement.
Both women had been due to serve until March 2004.
The Commission was set up in 1999, a year after the signing of the Agreement, with the aim of ensuring that human rights would be fully and firmly protected in law, policy and practice.
