O'Brien was undertaking a mystery stunt for the show on Friday, but things went awry and he was rushed to the hospital.
Bosses at network NBC have refused to reveal how the incident happened, or the host’s current condition.
However, the star seems to be lighthearted about the whole affair, saying in a statement, "Last thing I remember, I was enjoying the play with Mrs. Lincoln, and the next thing I knew I was in bed being served cookies and juice."
It is not known if any of next week's shows will be cancelled due to the accident.
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