The country's largest medical association is set to issue a formal apology today for its historical antipathy toward African American doctors, expressing regret for a litany of transgressions, including barring black physicians from its ranks for decades and remaining silent during battles on landmark legislation to end racial discrimination.

The apology marks one of the rare times a major national organization has expressed contrition for its role in the segregation and discrimination that black people have experienced in the United States.

In a commentary in the July 16 Journal of the American Medical Association, Ronald M. Davis, the organization's immediate past president, noted that many of the organization's questionable actions reflected the "social mores and racial discrimination" that existed for much of the country's history. But, he wrote, that should not excuse them.