The former US President George Bush Snr has been taken to hospital after experiencing shortness of breath, his spokesman has said.
The 90-year-old was taken to Houston Methodist Hospital in Texas by ambulance late on Tuesday as a "precaution".
Spokesman Jim McGrath said Mr Bush "will be held for observation".
The 41st President of the United States spent two months at the same hospital at the end of 2012, where he was treated for several health concerns including a bronchitis-related cough.
Earlier this year, Bush Snr celebrated his 90th birthday by making a tandem parachute jump near his summer home in Maine.
He most recently appeared in public at an event at Texas A&M University in November. He was accompanied by his son George W. Bush, the 43rd President of the United States.
George H.W. Bush took office in 1989 after serving two terms as Ronald Reagan's Vice President.
His term was defined for many by the 1991 Gulf War in Kuwait.
The Republican was succeeded by Democrat Bill Clinton in 1993.
President Obama and his wife Michelle have been notified about his condition and "send their good wishes" to Mr Bush and his family, White House spokesman Eric Schulz said.
