Tuck spokesman Joseph Ammerman said the lieutenant governor left Saint Dominic-Jackson Memorial Hospital shortly before noon Friday and is feeling much better.
Tuck, 41, plans to continue her recovery at home, and it's not clear when she'll return to work.
Tuck had been in Saint Dominic since Sunday night, shortly after she worked part of the day at the Capitol. People who saw her Sunday say she appeared weak.
Tuck's first round of hospitalization was April 17-21 at the University of Mississippi Medical Center. She was then diagnosed with mycoplasma pneumonia, sometimes called "walking pneumonia.''