Roberts, a breast-cancer survivor battling myelodysplastic syndrome, was scheduled to begin a leave from "GMA" late next month or in early September so she can undergo a bone-marrow transplant, but announced she was beginning her break effective immediately.
"Well a full disclosure here, I'm not feeling too well," the New York Daily News quoted Roberts as saying mid-way through the program. "In fact, I'm going to leave, and let you all do the rest of the program on your own. I'm going to take a little time off, just to get some vacay. I'll see you in a couple of weeks."
ABC told the newspaper Roberts is expected to return to the show in mid-August then leave again for her operation.
"Our Robin Roberts, we love you. Get a little rest. Take a week off, take two, then come back," weather anchor Sam Champion said on Tuesday's show.