NEW YORK (October 11, 2012)--ABC's Robin Roberts is home from the hospital three weeks after receiving a bone marrow transplant.

After thanking her doctors and nurses and singing "Amen," the "Good Morning America" host began the next stage of recovery from MDS, a blood and bone marrow disease.

Her sister was the donor of the bone marrow.

While leaving the hospital after a month is a big first step.

Roberts' doctor explained that it still will take time for her to gather strength and build up her immune system.

"Good Morning America," now the top-rated network morning show, aired a story about Wednesday's homecoming.

The show has brought in occasional celebrity guest hosts such as Stephen Colbert to fill in for Roberts.