Siriraj Hospital (Thai: โรงพยาบาลศิริราช; RTGS: Rong Phayaban Sirirat) is the oldest and largest public hospital in Bangkok, Thailand on the west bank of the Chao Phraya River, opposite Thammasat University's Tha Phrachan campus.

With a capacity of more than 2,000 beds and visited by more than three million patients per year Siriraj is one of the largest and busiest medical centers in Southeast Asia.

The hospital was founded by King Chulalongkorn in 1888, two years after a worldwide cholera outbreak.

It is named after the king's 18-month-old son, Prince Siriraj Kakudhabhand, who had died from dysentery a year before the opening of the hospital.

Siriraj was the residence of the late King of Thailand, Bhumibol Adulyadej, from September 2009 to August 2013.