Agriculture Commissioner Ron Sparks won with 65 percent to 35 percent for U.S. Rep. Artur Davis.
Sparks had the backing of major black political organizations that were spurned by Davis.
The chairman of the black Alabama Democratic Conference, Joe Reed, said Davis was hurt by rejecting the African-American groups and by voting against the federal health care plan.
Sparks said it helped that he went after every vote, and his call for an education lottery proved popular with primary voters.
Davis conceded in Birmingham, where he said he would support Sparks in the general election.