The details of his condition remain unknown though he is described by several sources as "very ill."
Early on Friday White House press secretary Kayleigh McEnany confirmed the hospitalization to ABC News, and later the president addressed the situation.
"I have a wonderful brother. We've had a great relationship for a long time, from day one," Donald Trump told reporters. "And he's in the hospital right now, and hopefully he'll be alright, but he is pretty -- he's having a bad time."
Sources told ABC News the president is expected to visit his brother today, though final details were still being worked out.